The one on the left has their arm in flexion, making their bicep contract, making it shorter and rise up like that. The one on the right has their arm in extension and therefore the bicep is longer and less exposed. We also know nothing about hydration, and all sorts of other things that would make the perceived size of their muscles different.
TL;DR your argument seemed disingenuous or misinformed. I am guessing that is the reason for down votes.