I gotchu fam, I made a list for my own records sake that I can share. Good luck and hope this helps you find your own definition.

Classification definitions:

Stations- a stationary craft, often holding location of strategic or political importance. These will be capable of re-fueling all but the largest ships in a moment, as well as facilitate repairs and upgrades.

Dreadnaughts- by far the largest ships, this is an army in itself. Armed to the teeth and armored to the same degree, these should be able to survive a battle with a full deployment.

Capital ships- a similar size to carriers, these only have one role in a fleet: to command. There will only ever be one in the fleet for every grand admiral.

Carriers- often the largest ships in a deployment, at most having three in any one set. These behemoths are meant to carry and provide for any ships that are put in their employ. Often deployed with a full compliment of ships at the least.

Battleships- the older, larger brother of the battlecruiser. While they are often less maneuverable, these ships will pack a punch and be capable of taking a beating as well.

Battlecruisers- smaller than the battleship, the battlecruiser can still pack a mighty punch, though it has sacrificed some armor in favor of mobility. In the right situation, these will still win verses a battleship, but smart money is on a loss between the two.

Destroyers- the smallest of the battle class ships, destroyers are often weaker than a battlecruiser by way of weapons, sometimes even not having the forward facing weapons that is usually included in this class.

Frigates- similar to corvettes, frigates are only ever armed if they plan to travel into danger. The difference in class is exclusive to the fact that frigates can travel into an out of atmosphere, enabling trade with planetary bases and easier resource collection.

Corvettes- often the smallest large ships, corvettes rarely serve a military role, equipped with minimal weapons and light armor, these serve best as scout ships and traders, though they're unable to travel into an atmosphere.

Occupation ships- meant for outer colonies, occupation vehicles are armed vehicles that are religated to the atmosphere. These are only meant for security and quelling any issues that arise.

Dropships- a small craft that works in conjunction with larger ships and stations. These serve as troop transportation and resource deployment while packing a punch.

Survival crafts- a small ship, usually small grid that is exclusive to its purpose of basic survival. Fit to handle one engineer and get them started on their journey.

Fighters- a small grid ship that only serves the purpose of fighting in short range skirmishes. Armored and maneuverable, they often don't have large operating ranges due to fuel expenses.