Confusion of game center vs facebook, etc

[HausOfSpin]

Hi there

I'm a bit confused about the current methods of identifying a player for a game, from a developer point of view.

When you have an active game center profile, can that automatically be your game profile, eliminating the need for a signup process or signing in with facebook?

it seems that you might want the player to log in with facebook even if they have a game center profile, so it's not clear to me how these two things jive with each other.

thanks for any input!