I think the first work still needs a bit of work. I'm still not feeling his right arm. His wrist seems to be meshing with his thumb bone, and that arm also looks kinda short, when compared the folded left arm. His lower abdomen (6-pack) is a little larger than a normal person's anatomy would allow.
However I do like the style it was drawn in, so no crits there. I think you got the main point of human anatomy down, but you might need to touch this guy up a bit. As for the bottom pic, I have the same crit as Dhaos, mainly about the strange orange colored object coming from his chest. But at the moment, I still would like to say that your style is top notch. Keep it up...