While the core games are all the same it really depends which system he is using. Exalted is a bit different from World of Darkness which is different from Scion. And the older editions are again similar but still different. As White Wolf doesn't have a purely post apocalyptic setting do you know what he is using?
Character creation is a dot and point based system. There are 9 attributes (and there is some difference between games). You get X, Y, and Z points to place in Physical, Mental, and Social abilities. The numbers vary from game to game as well.
Abilities (what d20 calls skills) are either done either in the same way (different points for physical, mental, and social abilities) or just a bunch of points that one divides up. Some of the games have a three dot limit.
Most of the games have a merit and flaw system. And there are other odds and ends that differ from game to game.