Self-mastery is a point of having command over yourself, your own abilities, your own desires, and being able to discern from protectionism and process. It is your ability to move through your life deliberately and with ease. Perfectionism many times can be fear-based, such as, “I have to do this exactly right so I can be seen in a certain way.” This is the difference. A person who is not developed in self-mastery will be a perfectionist. They have to prove what they doubt.