Ronnie's chest looks really deflated there compared to Jay's. I think by now it's obvious Jay has thicker skin than Ron, thus creating the illusion of higher bodyfat. They really have very different physiques, so it's hard to compare.
Yeah, I take your point- they do have different physiques. Though I think the chest thing can be explained by the fact that Ronnie appears to be pulling his elbows back more- this always stretches your chest out.
It's just that Ronnie seems to have a much higher muscle maturity- check out his legs- though, yes, I guess this could be explained by the thicker skin on Jay you allude to.