you can add more contrast and better define the form by painting in a light source. universal approach for this is to define the light as if above the character.
they will be different because they got different materials, the UVs just define where on a texture to get the information from, the materials define what the information is.
jocose: That's not exactly right. :\ That is a 2d art tutorial. In 3d: Specular maps define the brightness/color of a highlight. Gloss maps define the size of a highlight.
I stumbled on this recently, a really good overview and dissection of what makes a great game level. Worth a watch/read; good stuff! Designing Action: Defining the Encounter in Games