They overlap in meaning. They're not exactly the same and not completely different. Sometimes they're synonyms. "Bang" emphasizes the loud sound, usually a sharp, surprising sound. It suggests something strong. It suggests an explosion, a crash, and serious damage. "Bump" emphasizes the physical shock. "Bump" usually suggests something mild. A soft collision, followed by the two objects bouncing away from each other. If you think of it as making noise, you think of it as a "dull thud," not a "bang." You can say "The drummer bangs the drum" but you can't say "The drummer bumps the drum." You can say "there was a loud bang from the firecracker," but not "there was a loud bump from the firecracker." If you are in a plane and flying through rough air, you might say "We hit a lot of bumps," but not "there were a lot of bangs."

What do you mean what's the difference? They could be the same or completely different out of context. Have you tried looking them up in the dictionary?

"No two words are the same" as the Oxford Thesaurus says. I recommend buying a thesaurus which is a book of synonyms and it's really useful. In this case this verb is interchangeable when it means to hit a part of your body:The kid bumped/banged his head here the only difference would be BANG is definitely more used but there are other meanings bang can have a sexual connotation and bump has other meanings too(lots of meaning actually), I suggest you learn all of them little by little and check the other meanings at online dictionaries like merriam webster or dictionary.com. I hope this helps. Tony. Bye for now.

There is no difference. These words are synonyms.