Here's what I thought of some similarities: (based on colors, texture or design)
- Phobos > Deimos
Caduceus > Ragnarok
Vertigo > Monolith
Elemental > Scorpion (?)
Sentinel > Juggernaut
Scylla > Photon (?)
Radium Alpha > Osafune
Thor's Hammer > Behemoth > Ahab's Revenge
Goliath > ????
Hyperion > ????
Ellipse 1 > ????
???? - probably new ships will come up soon?
Bonus:
Since Phobos and Deimos are quite similar, I come up with a "Super Skill combo" like a Cross-shaped attack (both line and row damage) lol.