For capital ships I found my options much more divergent from the base game, in vanilla Sins you have 6 capital ships to choose from that all fill different roles, and you build one based on whatever suits your needs, however as the Empire although there were 7 types of capital ships only 2 were available to me at first, the Victory Star Destroyers, the Venator was locked behind a simple level 2 tech, and the Imperials and Tector behind logistics technologies, which I tend to stall on researching because each applies a global income penalty for the rest of the match.
however it seemed to lack the support cruisers of the vanilla game, instead simply offering up different variation of the heavy cruiser with different abilities and an interdictor. The first thing that stood out to me was that the roster of ships was modeled after the vanilla rosters, with a light frigate, missile frigate, siege frigate, defense frigate, etc. Upon starting a match everything will be very familiar and predictable, you start with some factories and scouts depending on your settings, for my first impressions test I played as the Empire under Darth Vader, and so I immediately began to take inventory of what was available to me. So right out of the gate if you're looking for a good way to recreate some epic star wars battle or are otherwise in it for any sort of immersion this is NOT the mod for you, however with that out of the way let's dive into the actual gameplay. This is not a mistake for better or worse. The first thing you will notice when you start a match of Interregnum is that you can still select any of the vanilla factions, and that while the Empire has a loyalist/rebel split, the Rebel Alliance does not. E4X is of course, like any mod, not without it's issues and Interregnum really hurts when you realize that not only does it carry over these issues, it has it's own. However Interregnum brings some unique bits to the table that it's cousin Sins of a Galactic Empire doesn't, namely it is an expansion of the excellent E4X mod which builds upon the DLCs for Rebeliion and aims to make Sins feel more like a proper 4X than a typical rough and tumble RTS that snuck into the 4X club with a fake ID. Star Wars Interregnum is a mod for that space RTS behemoth Sins of a Solar Empire Rebellion proving once again that the real time 4X genre was more or less both invented and perfected in 2008.