Not All Kardashian Butts Are Created Equal ...

7/21/2010 10:00 AM PDT

Not All Kardashian Butts Are Created Equal ...

Two hot sisters ... two great physiques ... one massive difference.


Yesterday, Kourtney Kardashian (left) took her booty out for a stroll in Cabo ... and unlike her little sister Kim (right), she managed to fit her entire ass into her swimwear.

Question is ...