I can't compare it to
Forza Motorsport 5 as I haven't played that, but I can compare it to
Forza Motorsport 4 which I played for 3 years before moving over to GT6.
From my experience of using both, here is what I think each can do better than the other (for reference, both pics are unedited):
Gran Turismo 6
- Camera height,
- Available camera angles,
- Camera Placement,
- Aspect ratios,
- Horizontal/Vertical images.
Forza Motorsport 4
- Depth of Field control,
- Colour vibrance,
- Camera movement controls,
- Shutter speed control,
- Brightness/Contrast settings,
- Lighting control.
This is a comparison of the Photo Mode and camera tools only; GT6 has the advantage of time of day and weather settings, whereas Forza 4 has more car customisation options and the livery editor.