These are all versions of the same song that can be used in different contexts throughout a game.  The first one is better as a standalone song, though it is still quite short.  The last three are better as bgm because they don't really have a climax per se and are thus more loopable.

I really like it when a certain song appears throughout a game with different instrumentation or different effects to change it up a little (e.g. Eyes on Me in FFVIII), so maybe these can be used to that end.