The difference between an Animagus and a werewolf is that an Animagus elects to turn into an animal but a werewolf has no choice. After the person has transformed into a werewolf he no longer remembers who he is; he would kill his best friend if he got anywhere near him. A werewolf only responds to the call of his own kind. The only way that a werewolf can retain his sanity, intelligence and memory while transformed is through the use of the Wolfsbane Potion.