nah they're the same but different. they're running on the serious engine 3 so everything looks nicer. but since the 360's hardware can't push the engine well, the game is capped at 30fps.
it also includes Serious Sam 3 and Serious Sam Double D XXL (if oyu're talking about the collection) which comes with the DLC for Serious Sam 3.
Fantastic games. pretty much the same content as Serious Sam Gold but looks nicer and no extra life system. you have checkpoints instead. I'd say pick up the collection. It's worth it. But if you have a PC that can run them, get it there. Much better experience. And there's tons of mods in the Steam Workshop.
See The Game Collection http://people.ign.com/nights_team2k7/games