The other portraits look painted, whilst the lizardude's portrait looks a lot more.. pixely. All the detail and attention to pixels (Thin lines and outlines and such bring them out) seem to differ from the rest of the portraits style. They seem to rely more on shading and coloring, with thick black outlines.
It's almost as if 2 different people drew the portraits.
But they look good, nonetheless.
I really like the sorcerer, good pose, as well.