There’s 2 degrees or more difference in the head angle. The Prophet is very much the more “fun” bike, and the Rize the more serious all day XC kind of bike.
Prophet is also significantly better VFM I’d say, but then its a frame design that has been around for a good few years now (with good reason I say). In fact, it has already been dropped in many international markets, including the US (do we get to keep it for 2010 still? I hope so!).
Weight wise, ally Rize is marginally lighter than a Prophet, but there’s not a huge amount in it. Only half a pound or so in the frame, a bit more in the componentry.