Usually for school or work as excuses. Lol
But I also explain a lot if Im sorry about something.

Explanations are offered out of guilt, while excuses are offered as way out of responsibility.

I don't make excuses ,it is what it is

My cat ate my homework lol

I tell people all the time my reason for something or another, but am clear that I realize it's not an excuse and don't mean it to be...just an explanation.

I think there are different intentions behind the two.