The lats are the biggest difference for me, just look how they just flow down in the second one. His lower and outer chest also look a lot better to me as well. His traps are almost non existent in the first one, but im going to chalk that up to posing issues.
But for the most part I think your right, lower body fat and better posing. Little changes, but they add up.
ORIGINAL: David1991
the peak is only different because of how much more he's curling his arm. and the "seperation" is only from being leaner which could be done in a few weeks from the first pic. if u look at overall mass he doesnt look much bigger at all, just more contest ready.