how come the same games for both systems (xbox360 & ps3). The 360 ones have better reviews?

i dont understand this, and it was also the same in the last console generations, usually the xbox games were ranked higher than the ps2 version.

var:http://www.mozmar.com/how-come-the-same-games-for-both-systems-xbox360-ps3-the-360-ones-have-better-reviews-27828.html