The top one looks like the C4 w/ aerokit we have seen, it has red brakes and rides higher. The botom one has PCCB's, rides lower, and specially centre exhaust like we have seem on other 997GT3 spy pics and in the 997GT3Cup.
I like the centre exhuats on the GT3 version very much, not becuase the look good (not to me)but becuase there won't be as many carrera-aerokit with fake badges walking around

BTW, Thanks a lot Darius for posting!