Well a founder (not available anymore) grants access to the beta and gives the full game when available. It also gives that spiffy founder badge.
The founders elite, grants access to the alpha / beta / full game and all expansions and DLC for the game. It also gives that spiffy founder badge and the ability to name a star.
These are the things that I can remember. I think there is a special thanks in the credits as well. I'm sure stardock will correct me if I'm wrong.
