This is a difficult question. Hope this helps alibi noun a claim or piece of evidence that one was elsewhere when an act, typically a criminal one, is alleged to have taken place. So an alibi is the proof that you were not in a location and is generally used in law. Excuse noun a reason or explanation given to justify a fault or offence. So an excuse is just an explanation. It is not necessarily linked to location and does not have to be true. For example Where were you on Monday? I was with my brother the whole day. The alibi would be the brothers testimony that he was not in the location. The excuse would be that he was with his brother