From publisher's website:
The hardback edition has the same full-color, 208-page interior as the exisitng softcover rulebook - in fact, the interiors were printed at the same time. We've just put a fancy new cover on these copies to entice those gamers who want a classier version of the game.
There are two new covers. The "angel" version features the In Nomine logo and a stylized cross in red foil on a white faux leather cover. The "demon" version comes in black ... with the cross inverted.