Xbox looks slightly better, but to be honest there isn't much difference in it. It's hard to tell with slightly different angles/lighting. Could be possible one mission was played earlier in the day, whereas the other was played slightly later? Hard to tell
Both looks pretty much the same to me. You wont really notice minor differences like this when the game is in motion. The real difference will be performence (Frame rate etc) But both seem to run fine from the different gameplay videos/reviews and any differences
in brightness/contrast can simply be changed in the options to get it how you'd like it.
Particularly in the second comparison the brightness setting look to be completely different, either that or they were played at different in game times. I think both versions will be more or less the same.
Again I can't really tell a major noticable difference in that video. Those type of comparison videos aren't that great IMO where the image is split, what are you suppose to compare when both sides are at different parts of the screen? I prefer the same
footage from both consoles side by side, I find that to be a better comparison.