Cruiser - the term cruiser is applied to any spacecraft that can operate at interplanetary ranges without refuel or resupply. Ships that travel from planet to moon, or moon to moon in the same planet's gravity well as not considered cruisers.
Supercruiser - the term supercruiser is appled to a spacecraft that can operate at interplanetary ranges and function for years at a time without refuel or resupply. Supercruisers are typically also highly specialized ships, and many are one of a kind builds. Supercruisers also are almost always megaships as well.
Megaship - Any spacecraft over a kilometer in length, capable of moving at a minimum of 1G acceleration. Any craft unable to meet this speed requirement is considered a mobile habitat/station. The anchorages of the Atlantic Federation are size and endurance wise, but are only capable of 0.25G acceleration.
Bulk Mining Supercruiser
The Bulk Mining Supercruiser is a catchall term for the various large superheavy mining ships that are active in the asteroid belt and other space environs where there are chunks of space rock to be prospected, and processed. The average bulk miner or asteroid miner resembles the offspring of a cement factor, starship, and robot squid. The bulk miner will 'embrace' it's target asteroid with it's appendages and lock it to the ship. Then, the mining crew will start hollowing out the rock, and will use said extracted material to form their common areas and barracks inside the rock, turning it literally into part of the ship, until the mineral resources are exhausted. Once this is done, the giant ship will offload it's semi-refined ore to it attending fleet of ore haulers (automated process) and will detach from the asteroid. Smaller rocks are pushed into terminal orbits with either Jupiter or the Sun, or on trajectories that will send them out of the solar system. Larger rocks, complete with built habitation space, ray shielding, etc, only need moderate upgrades to become space habitats, and many are.
Bulk Mining Ships are typically corporate territory and subject to corporate laws, and not any terrestrial nation. As such, the bulk miners operate in their own socio-political environment, and each ship can be its own microcosm of society. There is no way to pin down the normal ship crew, or normal routine, as each ship, operating for years, or even decades with slow crew rotation, will grow into their own creature. For each hyper-patriotic corp 'cruiser there is a scum barge full of cyberpunk lowlifes.
Farm ships are relatively uncommon, megaships are expensive, and farming has never really been a high profit margin operation. The agricultural supercruisers are minimalist ships, a command section, dozens of agro-domes, a central spar, and a drive section. These ships operate, keeping their axis rotating and growing bulk high value crops in their domes. This isn't wheat, soy, and corn, but rather pharmaceuticals, botanicals, high end produce, luxury produce, and flowers. These ships have regular paths they make around the sun, allowing for merchantman and trader ships to reach them and carry out their transactions and bring these perishable goods to various moons, colonies, and stations. These supercruisers are capable of self defense because there are pirate sorts who would hold them ransom, or rob them of their biomass cargo, or just pillage them for parts, fuel, and pressganged crew.
The Lunar Free State, Jovian Lunar Alliance, and Mars interests support most of the Agricultural supercruisers and are willing to defend them, even if the supercruiser in question isn't theirs. This mutual defense is the beginnings of an outer system friendship and potential seed of organization outside of Terrestrial nations influence. It is worth noting that there are agricultural supercruisers that 'ranch' and free raise livestock inside the domes, and that there are aquacultural domes for fish and shellfish production.
Bulk Cargo Supercruiser
These ships are rare, massive vessels that have regular shipping lanes between Earth, Mars, and Jupiter. The ships are largely automated, and carry high volume low value cargo, typically mineral ore, and unrefined hydrogen harvested from the extractors above the gas giant planets. While capable of 1G acceleration, most cargo supercruisers seldom move faster than .25 or .33 G for reasons of fuel economy, and their cargos are neither perishable or urgent. Most refineries and other facilities that they service have them scheduled for when they arrive, and big fuel refineries might have their schedules docketed for years.
Bulk Cargo ships are the least glamorous ships in the solar system, big, slow, and even pirates have little use for them. Corporations and nation fleet assets are more than willing to murder every pirate they find, and in the case of a hijacked cargo ship, even the most even tempered nation has found it quicker and easier to just perforate the crew area, pay out the contracts to the next of kin, and throw surviving pirates out the airlocks.
Dredgers are large and important ships in the Cosmic Era. They have large magnetic ramscoops that they use to clean space lanes. These ships gather up dust, and other space trash, like errant bolts, wreckage, and the rest of the high speed debris that can damage ships in transit. As such, they are constantly moving, sucking up and cleaning space around them, and are periodically visited by cargo cruisers where their trash bins are emptied. There is some recycling on the ship, the dredgers can harvest interplanetary hydrogen for fuel, and anything usable is used. Also called Scappers and Scavvers, these ships are massive, dirty, and range from boring to highly profitable, depending on their paths. There are almost always several dredgers operating in Earth orbit, there are centuries of space trash to clean up, and every accident, launch, or spill just makes more mess.
Dredgers are popular in sci-fi media, as they are the ships that are most likely to find things. This can be finding horrible things like diseases, aliens, or sentient weapons, or mysterious things like derelict ships, lone survivors in escape suits and pods, to breathtaking things like long lost treasures. The truth is completely non-glamorous, as Dredgers are the CE's street sweepers and trash trucks.
Penal Supercruisers are massive prison ships. These ships are thankfully rare, and are mostly used in the highly questionable manner of keeping large numbers of prisoners out of the judicial system, in a sort of pending limbo. This is done part as a way of reducing the backlog on the system, and keeping inconvenient prisoners out of the loop. The penal supercruiser is a space gulag.
Penal Supercruisers are deep space prison ships, to get the right vibe all that is needed is to put Alcatraz or Shawshank in a metal bottle with large engines.
The Science supercruiser carries out its research well away from Earth, typically working away from EM noise and distraction of the homeworld. These supercruisers are covered in deep stellar observatories, exotic labs, radar domes, and the other apparatus of high flying science and arcanotechnology. Once in position, most of these rare ships seldom move, unless it is to reposition, or return to base for repair and refit.
The dark side of the scientific ship is that what is done on these ships is done outside the legal boundaries of nations, and out of public sight and oversight. This is the theatre where the most vulgar crimes against nature, humanity, and god are carried out. This is the arcanotech version of the ortolan, and the men and women who carry out these technological abominations do so under a veil of mysticism and occultism.
The Tanker supercruiser is a variant of the bulk cargo ship designed to carry liquid cargo. The most common liquid cargo is water, typically harvested from comets and space dust. This is used to fill aquacultural stations, and in terraforming operations on Mars. These water ships are typically running very long routes between the inner and outer solar system and on long timetables. Some tankers will allow their cargo to freeze and prevent leaking. Fuel tankers are also present, but most will carry their cargo in a compressed gaseous state, rather than going through the considerable effort to reduce hydrogen to a liquid and keeping it there. Volatile gases and liquids like methane, ammonia, and hydrocarbons are less commonly trafficked, but they are still out there.
Water ships are a vital, if boring aspect of space traffic in the CE
In the event of a space accident, time is of the essence. Rescue operations cannot be launched from Earth and expect to arrive anywhere outside of Earth space in a reasonable amount of time. This is more paramount when the object of rescue is a heavily occupied cruise liner, space habitat, etc, where there are large numbers of people, and a very limited window of opportunity. Rather than having ultra-fast rescue ships, there are a number of rescue ships that are maintained in a general state of readiness. In the event of an accident, the rescue supercruiser can rapidly respond to an accident site, and has the room to take on hundreds or thousands of survivors, treat them medically, and even participate in recovery operations. The rescue ship's large engines make it fast, and once on the scene, docking arms and maglocks can allow for the rescue ship to grab a damaged ship or station and return it to a safe port of call.
Rescue Ships crews are cowboys in space, who spend the vast majority of their time waiting for something to happen.
Also known as generational ships or high speed stations, Hab-Ships are supercruisers built to be self-sufficient and to travel long distances at extreme efficiency. The ships have impressive cargo capacity, resource harvesting abilities, and self defense weaponry.
There are a number of hab-ships that are well away from Earth on their lofty missions to take humanity to other stars. The Oumuamua is a massive ice clad hab-ship on a long duration mission. A quartet of supercruisers were launched early in the Cosmic Era and contain almost no arcanotech, the Argo, Reagan, Sarengo, and Nagglfar. The 'Megaroad Project' saw a union of early megacorp, AtFed, and other assets to build these four ships and launch them towards a potential colony sector beyond the solar system. There is some popular speculation over the fate of these ships and the hulk of the Nagglfar was found at the edge of the Oort cloud, and data torpedoes from the Sarengo were found, but the data was corrupted and incredibly strange. It is assumed that eventually the wreck of the Sarengo will be found, but there is no trace of the Reagan or Argo. The wreck of the Nagglfar showed that its prototype AISC, ATLAS, was sabotaged, but the data cores are either heavily damaged or simply wiped.
Detention Ship - any of the above ships (bar the penal supercruiser) can be a Detention Ship. In a detention ship, the majority of the crew is of criminal nature, typically low level offenders with high levels of valuable skills. Offenders are given the option of a long prison sentence, or a preset amount of time serving on a detention ship. While boring, this is generally much shorter, and allows both the offender to get out relatively quickly, and the corp/state gets a cheap employee and not another person in a prison. Corporations are the most likely to operate detention mining ships, while nations and states are more likely to have detention argricultural and cargo hauling ships.
Security Ship - the security ship is a military vessel, a Q ship, that has the appearance of a civilian supercruiser, and acts as pirate bait. The ships are armed, and typically have decent aerospace assets. This allows security ships to project force where it is unexpected. In heightened threat situations, security ships can be held close where their guns and fighters can be an unexpected asset.
Potemkin Ships and Spidireens - Potemkins are facade ships, an outer hull with a skeleton crew, and almost not actual capabilities. There are a handful of potemkins that are known as used as training ships, training for rescue ops, or for escort training. In the case of severe pirate threats, potemkins and security ships can be used to create super targets for pirate attack, posing as large high value convoys. In times of war, this tactic can also be used to throw off enemies who are convoy hunting. Spidireen ships are ships that only exist in records, false ships. Corporations have spidireens to throw off investor investigations, or to spoof their competitors. Nations can have lists of spidireens to operate as fronts for fleet operations.
The roles of civilian cruisers has been covered in non-military cruisers submission, but there is no reason for there to not be supercruiser versions of these ships.
Diplomatic Supercruiser - the diplomatic supercruiser is a flying piece of terrestrial sovereign territory. Most of the time, the residents of the outer solar system dislike the appearance of these largely unique ships because they most commonly appear in a commissariat oversight role, where they impose their legal sovereignty over whatever location they enter, a sort of fusion of eminent domain and manifest destiny. In the CE, this is a conceptual ship, and most of the advanced Federation class battlestars operate as a military version of this. If the Atlantic Federation did field such a ship, it would be escorted by at least a battlestar and would function like Airforce One, having all the resources of a government in exile or a government at war.
Megacorp Supercruiser - eventually the megacorps will either dominate the governments, or their industrial and technological power will allow them to relocate. The megacorp supercruiser is a mobile megacorp, allowing for the full operation of said corp to be held without being beholden to any terrestrial government. In the CE, the Five Metal Dragons mining consortium are the most likely to field a megacorp supercruiser, and it would basically be Ceres given spaceflight capability.
International Supercruiser - born from the Legate cruiser, the International Supercruiser would by the flying flagship of an international organization similar to NATO or Interpol and would combine legal jurisdiction, rescue ops, and security ops in a single superhull. This ship is specifically not intended for ship vs ship combat.
Relay Supercruiser - the relay supercruiser is a megaship space relay, with a minimal crew. This ship is simply a much larger version of the CognoComm cruiser. In this situation, the relay supercruiser would be the hub of a communications fleet, serving a group of CognoComm cruisers, and providing the main data trunk back to wherever home base is.
Shipwright Supercruiser - NOMAD is a shipwright supercruiser, a multi-kilometer long ship construction facility. Facilities like NOMAD build large cruisers and habitats in locations where it is easier to build on site than to build and then shipping the product there in one piece. Given the mass of habitats and stations, this is generally the case.