I really don't see the difference between those two pictures, and I'm no stranger to bodybuilding. He's flexing hard in the first one, totally relaxed in the second one. To the people saying his neck looks bigger in the first one, well, that's because he's raising his traps up to his ears. I can do the same and achieve the 'no neck' look, even though I don't look like that when walking around normally.
The only picture comparisons I've seen that highlight any real difference have been the ones comparing his current physique at 155 with his former physique at 170. He might have been juicing, I don't know, but any armchair M. D. claiming to be able to see the difference is full of shit.