While resolution is easy to quantify, it is a number the overall IQ is not.
720P 2x AA on 360, but it has slightly more pop-in and some strange dithing artifacts.
640P 0x AA on PS3, but no artifacts and has some post-processing filters to soften the IQ.
In the end most reviewers could hardly tell them apart, some said the 360 version looked a sharper (as it should), but also said they like the Ps3 version look more.
The PS3 version also has the HD install which has faster loads and less of them.
What is ironic thing is one day (IGN review) the net is on fire with saying the PS3 is better, then later it's all about 640P (which they report wrong). So anything for hits I guess.
Now playing: DA:I, GTAV
Recently Finished: Far Cry 4, Infamous: First Light
PSN & XBL: Scuzzlebutt33