Just looking at IL2 compare the only real performance difference I see is level speed, the C being anywhere from 2 to 4 kph faster. I have no idea why. It would have been cool to have an early B (no fuse tank and -3) and a late C (fuse tank, -7 and dorsal strake). I don't know what the rationale to include two different models (in name only) with identical performance was.

If you get to looking at any of the game's planes TOO closely you'll find issues with virtually every single one, so I TRY not to - lol.