Basicly from the modding perspective there is only 2 classes frigates and capitals. The difference is the way their file is built and other limits like only capitals can get experience and frigates can be deployed by abilities while capitals can not. Also only frigate type files/entities can be build in the factory, while only capital files/entities can be build in the capital shipyard. You can implement more classes by giving ship different research requirements so that there are some that you start with and then there are those who require more resources and higher level of research.

“Autocast is a feature that allows the player to delegate the use of special abilities to the AI...

Autocast

Active vs. Passive

“A frigate is any Entity with the EntityType "Frigate". Frigates are constructed at the Light...

Frigate Modding