Looking here and there appear this is a standard operation in game engines, where you need low poly models looking as good as the high poly modeled and painted in tools such as zbrush.

Discovered tools such as xNormal or MightyBake that allow to compare the two versions and generate different maps (texture bake is the term I did find many times).

Now the problem is understand how to make it work with all the specific jargon about normals, UV mapping, textures etc.