What's the difference between an excuse and a reason?

An excuse is trying to say that there's a good reason for why something happened as if you shouldn't be blamed for it. As you can see, I used the word reason. In context, excuses (and reasons) are often seen as an attempt to subvert blame in a situation where the other person feels you are in complete control. If you find yourself giving excuses, you might need to reassure the other person that you take responsibility for your actions and see how you can work to rectify it.