Snakes that appear different than a normal looking one of the same species is called a "morph". The normal looking one is also known as wild type. The difference occurs in coloration and patterns. A physical difference is a genetic defect. So a snake with 2 heads is a genetic defect, but a spider ball python (picture on the right) and an albino ball python (picture on the left) are coloration and pattern morphs of the same species of snake. All species of snakes have genetic morphs.