phrases - Difference between "Excuse me" and "Sorry"

What is the difference between "Excuse me, ..." and "Sorry, ..."? When do we use one or the other?

For example, when you haven't heard the speaker, or stepped on someone's foot or accidentally spilled some sauce.

Answer

Sorry expresses more regret than excuse me does.

If I'm trying to leave the room and you're in my way, I'll say "Excuse me." I recognize that I'm inconveniencing you by asking you to move, but the inconvenience is very small, and I don't expect you to be offended by the request. People often say "excuse me" when they commit small violations of etiquette, such as sneezing loudly.

If I accidentally step on your toe while I'm trying to get to the door, I'll say "I'm sorry!" I didn't mean to step on your toe, and I regret injuring you.