You can't possibly compare them, I'm sorry... I do know a thing or two about the pretty pictures game and the AC stuff is real, un-edited gameplay. It's obvious by the bugs in the images alone... (he chuckled) ...but seriously, you can't compare em...
Why?
As much as Ross wants you to believe the image at the top of the forum is "in game" it's been clearly touched up with a soft vignette filter at least and at worst, the crowd in the background is an under-layer to the game-play capture in front. Also; Note the lack of shadows on the characters in the above image - either they're not rendered or the characters aren't fully interacting with the in-game environment. (Eg, the players have short small shadows but the stumps have nothing...) Until there's a Hi-Res back-up to compare one-to-one you can't begin to draw reasonable comparisons graphic-wise.
None of that is a stab at BA, but the new images from the AC title are pure, unedited gameplay. Some might say, a little TOO raw