While playing through the Imperium campaign, picking ships for fleets, I found very little difference between ships of similar size aside from armaments. While some had longer detection ranges or sported a bigger cannon/torpedoes/different cannons, hull and shield amounts and speed seemed to stay the same. It soon became clear to me while fighting Chaos ships that aside from nuanced details that I had to really zoom in to, I could hardly tell one cruiser from another except for a larger/smaller health bar.
For example, the Cobra and Widowmaker frigates have 50 armour per side while the Firestorm, Sword, and Falchion have 67. Shields across the board are the same, they're all 200 speed. Your light cruisers/cruisers/battlecruisers all have the same armour and shield amounts with the exception of the Dauntless Mk I and II, with slightly more front armour. Grand cruisers and Battleships have higher shields, but as much armor as a light cruiser?
It does not allow for much strategy or special planning and can mean even less to someone fighting against the Navy. If I were to face an Imperial Navy fleet, I could only tell the difference between ships because they are either visually bigger or their icon is bigger on the sidebar. Between cruisers, I had a hard time differentiating which ships were which.
If I could make a suggestion, have something more obvious/eye-catching to make a distinct differentiation for a player to make and come up with a better plan than throwing units at them. The Gothic could have something particularly shiny on it that a Tyrant would not have, the Lunar could move faster because it has lighter armour but packs a close-range punch. Maybe each hull type could have a clarion call or a number of lights matching the dots on their icon. There has to be something beyond "one has a big cannon and the other doesn't."