Same same same 2p version:
Blue ship (second player) does more damage, at least with the blue weapon. Haven't checked the otherr weapons.
Differences between 1P and 2P player sides (various games)
Re: Differences between 1P and 2P player sides (various games)
It does even more damage in Fire Shark than it does in Same! 2P, which is really interesting. I haven't played Fire Shark for quite some time and I don't remember for certain, but I am pretty sure you can kill tanks and boats and stuff with only one hit on 2P side in that game.