Tutor is a person who helps you study a certain subject outside of school if you have problems with it. They usually charge hourly for their services. Some folks on italki are tutors (i.e. they help you learn a language and expect you to pay for every lesson.) Mentor is an experienced person who guides you when you're just starting your career or engage in some other major activity . His advice is supposed to help you grow professionally/spiritually. When you're young, your parents are you mentors. Supervisor = manager. There may be a few differences, but overall they're the same.