These terms are used interchangeably today but the main difference is between hypnotherapy and the other two. Hypnotherapy is the main application of hypnosis today. It is a more specific term used for helping a person make changes. It can involve helping you let go of an emotional problem or improving your skills - by using the power of your mind. Hypnosis is the ma more about the process of helping a person go into a trance. A hypnotist is not necessarily trained in the professional skills of hypnotherapy. Hypnotism is the entire field of applications using hypnosis, including stage hypnosis