To me it's the size of the ab muscle that's popping through a layer of fat. While neither of these guys are truly fat, their body fat level isn't that low. Everyone carries fat differently as well. Some people may carry more in one area of their body than another. So while Ray Lewis in that picture is a little leaner than the guy on the left, the major difference is the lean muscle mass Ray Lewis has their. Based on the smoothness of the guy on the left he's really not that lean. If he wants more vascularity he needs to get leaner. I'm not an expert at this, but getting better at estimating body fat. He probably needs to drop at least 5%, maybe 7%-8% to really start becoming more vascular.
