to bang - to bump

[dilodi83]

to bang means 1) to hit something hard and loudly, maybe to express anger.
2) to hit a part of one's body by accident
to bump means to hit someone or something suddenly by accident without causing serious damage. It's often used with parts of the body.

Now, I understood point 1: the use of bang to express anger...but what about the difference between point 2 of bang and the meaning and the use of bump? Do you use them without difference?

Could you tell me how to use these two verbs properly?

[Barb_D]

Yesterday, I was rolling my chair further under my desk and my knee caught the side, really hard. It hurt a lot. I didn't look, but there is probably a bruise. I definitely banged my knee.

You bump something softly, and bang something hard.

You can bump into someone and they might spill their coffee. If you bang into someone, you might even knock them off their feet.