Better is relative when it comes to the same model of cards.
Try these reviews to add more light to the dilemma.....http://www.guru3d.com/article/msi-r5770-hawk-review/1
Now that's something of a dilemma, but I'd suggest the only point of variations may be the size and the decibel level, plus the number of moving parts.
In stuff like this, it's usually very very minute that we find a difference in specs, it's just these added goodies and the few bucks here and there that make the difference.
Yeah!! Not to mention the OCing factor......