teacher is a common word, everyone gives you instruction can be your teacher.

tutor is the person who gives private instruction

professor is the highest rank of teacher, it is a person who teaches at a university.

mentor is the person who specificly trains someone. for example, you need to choose a mentor when you start your postgraduate period.

Examples/ explanation:

Tutor is someone usua;;y paid for more assistance in math or learning a language.

Teacher is a general term you can use thrgoughout schooling.

Professor is used at thge college or university level as a term for teacher.

Tutor

A girl stays after school pays for lessons in Spanish. She pays a tutor.

Teacher

I had many teachers in school kindergarten to high school. I had a Spanish teacher.

Professor

I had many wonderful professors in college. Professor Dilla taught a graduate level fraud course and opened it up to undergraduate students.