Question: what is the difference between a muslim and a believer?
Answer: A Mo'men -مؤمن- a believer, is a step up from being a Muslim it's to believe in Allah, his angels, his books, his messengers and the day of judgment, and to believe in fate what's good of it and what's bad. you could say that being a Muslim is the work of the body, but being a Mo'men is the work of the heart.