I know this question could be too general and maybe not focused but i would like to have an opinion. I found these images from this link
I assume this is done by zbrush but what's getting me astonished is the vertex number... how can you create such a defined mesh with just 4000/6000 tris??? Is it a matter of 3d modelling program, modelling skill or it is just the texture that's doing all the job? Can i realize these meshes with few vertices using blender?