1 - in the car garage well, the xbox garage is actually there, but there is a lot of bloom (probably for those nostalgic of the early 360 days) and the bad use of depth of field kill all details... So GT7 wins
2 - During the race the lighting is way off in forza, the lights don't look like they are emitting light (they do emit light, but their appearance on the cars doesn't make it seem like so) same for how the light bounces on the cars backs, etc.
3 - The anisotropic filtering in Forza is just atrocious and kills all details, especially on the track
4 - The 3d crowd in forza will show up no matter when the race is and no matter what the temperatures are! which is great I guess, so the crowd wins for their dedication in forza.