Orbital Spacecraft (Shuttle)
The Orbital Shuttle is a spacecraft that is designed to leave a planetary surface, enter into orbit and return. It needs powerful engines to enable it enter into orbit from planets like Earth. The spacecraft's must be able to withstand high temperature and large thermal variations if it is used on a planet with an atmosphere. Shuttles on Mars need less powerful engines than Earth shuttles as escape velocity is much lower, and face less atmosphere on return. Image of small shuttle
Transfer Shuttles
The Transfer Shuttle is a space only craft that is designed to move from one orbit to another. A special case in point is Earths' Luna Shuttle.
Planetary Cruisers
Planetary cruiser is applied to small fusion powered craft, usually less than 20,000 tons that are equiped and able to accomplish interplanetary flights in system. This class of ship is the 'jack of all trades' and is used by by every group in space. These hulls became used by the military and became known simply as Cruisers. See More
Space freighters are spacecraft designed solely for the transport of goods between planets and moons. Freighters are not really a single ship class as they range from small single person craft to massive ships, many kilometers long. Note that many are completely automated, with a pilot on board only for docking.

The first freighters were created late in the 21st century to supply Mars and used chemical rockets. Next century large freighters were powered by fusion engines and capable of reaching the depths of the solar system.
Mining & Construction Ships (confabs)
"Confabs" are units designed for space mining and manufacture. They combine the features of an orbital factory, a variety of mining units and a spaceship. "Confabs" are not really a single class as they range enourmously in size and capability, with the largest believed to be the most complex machines ever built. "Confabs" are completely automated, a need for prologed missions in deep space that last many years. They are also largely self sustaining. Some of the most capable AI's yet developed are used to run the most complex confabs.
Space Tugs
Space tugs are craft used to move other space craft or barges of cargo. A pair of the larger tugs are capable of moving the even the largest space craft. Most Space tugs are short range, orbital or moon transit craft only, like the famous Dragonfly which can be found in orbit all through the system. The exception are the Deep Space Tugs which are capable of towing for long periods of time over interplanatery distances.
Deep Space Explorer Ships (DSX)
These large manned ships combine the features of a manned cruiser with the abilities of a Confab. They are able to run independently in deep space for long duration missions lasting years. The first ships of this type were the Odyessy Class which were the first ships to reach the outer planets.
When practical QLink was developed in the 23rd century the DSX ships were resonsible for the laying out of the Qlink relays and their long term maintenance.
Large passenger liners became possible with the advent of the fusion drive and large scale space construction. These ships are mostly greater than 100,000 tonnes and have a rotating passenger section to provide artificial gravity.
Miltary spacecraft range considerably in size and function, but generally fall into four broad categories – jumpships, dropships, cruisers and small craft such as fighters, shuttles and escorts. Military vessels are often accompanied by civilian support vessels.

Ships equipped with jump drives are known as Jumpships and range in mass from half a million to many millions of tonnes. The size is necesary to house the Fusion Array to power the jump engines. Warships, are an  armoured subclass of jumpship and fitted with  weapons. The size and delicacy of a jumpship's drive limits such vessels to space and precludes planetary landings. Jumpships use an array of fusion engines for power, needing at least XXXXX GW for transitioning
Dropships are fusion-powered craft built to transport people and cargo between space-bound jumpships and planetary surfaces, or between jumpships. Dropships have only a fusion drive for covering short interplanetary distances, for making orbital and atmospheric maneuvers, and for takeoffs and landings. They mass anywhere between 400 and 100,000 tonnes, and are usually of either aerodynamic or spheroidal configuration. Aerodynamic dropships trend to smaller and more capable of atmospheric missions. These are often refffered to as Military Shuttles. A common class is the Penguin. The civilian/commercial equivalent of a dropship is simply known as a shuttle.
The military Cruiser is a medium sized fusion powered craft, usually less than about 30,000 tons that are equiped and able to accomplish interplanetary flights. The hulls design are based on the civilian Planetary Cruiser class. These are the work horses of in system work. Like their civilian cousins, these ships tend to be the 'jack of all trades' for the military. Cruisers vary significantly in their armor and weapons. Many models offer different mission specific configurations. 
Cruisers are in system ships that make
The smallest vessels capable of space travel are known simply as "small craft", or as aerospace craft if capable of planetary landings in an atmosphere. They may serve direct military functions such as fighters or bombers, provide recon or simply provide transport.y

Dropships are a heavily armed and armoured craft used for landing and retrieving troops from a 'hot zone'. Small Dropships carry only a dozen and are aerodynamic and use aerobraking during rentry and display aerodynamic lift for true atmospheric flight. The largest Dropships, such as the Terran Osprey II are able to land upright in a relatively small area using 'reverse thrust', though are of of extremely limited range. See More >
A 'Space Fighter' is a term used to describe small, fast, usually one-person craft designed for combat in space. The Terrans' Boeing Starfighter was a space only craft. The Martians used the Firestar during the war, a winged craft capable of Martian atmospheric landing and even take-off, if supplied with extra fuel tanks.
The first generation of these capital ships were built during the war and were called battleships by both sides. The Terran Nirvana class, as reperesented by the SS Prometheus. and the Martian Ruby Class, SS Ares. This class of 'battleship' quickly grew in size and diversified into the the range of capital spaceships we know today, the Battlecruiser, the Carriers (heavy and light) and the Flagship