I want to show why, so let me break it down.
First, observe Tom's and Edmunds arms. Notice something? They are the same size. Actually, Tom's arms are a little more fattened, while Edmund's are more muscularly built.
Second, look at both of their faces. Tom's face is in more, his jaw bone is about aligned with his neck, making him seem average or skinnier. Edmunds face on the other hand, more specifically is jaw bone, precedes his neck, making his face seem wider and therefore making people conclude that he is large.
Inclusively, observe their shoulders. Tom's shoulders are a bit more sticking straight out, making his chestal area seem smaller because of the illusion. Edmunds shoulders are more rounded and therefore, what do most people associate round with? Big. Since his shoulders are rounded, and it generally gives his body look a more round disposition, it gives the illusion of him being large.
Last, look at Tom's belly. That ribbon is Curving! Around what? His bellay! Okay, maybe thats not so true.