The creators of this style of CC aim to create content that blends into the game as if it belonged there all along.
Maxis Match is pretty much what it says on the tin. Also I hear it takes up more space, and it's not always laptop friendly. Cons: the look is very different from the game's design, so your Sims will always stick out from townies unless you give everyone a makeover. Pros: very pretty, can get some sick looking stuff, is everywhere. You might have seen some people posting Sims with kind of wispy hair? That's Alpha.