It's better to think about the idea of a map rather than all the different kinds. A map has information, usually the values are stored as gray scale values. So one might be white and zero black. This can be put into a huge number of attributes to affect a mesh differently over its surface. For instance, a specular map will change which areas are more or less specular. If you know what an attribute does, then you know what a map of that attribute will do.