The point about 'report ... to' in these examples is that it has an official tone. You report something, usually a breach of some form of law, rule or code, to somebody who is in a position to do something about it . 'Relate' has more of an idea of just a narrative:
He reported the mugging to the police, and then related the events to a reporter.
'Inform on' has some overtones of doing something sneaky or ignoble.
In dictatorships, people are encouraged to inform on their friends and neighbours.
People who inform on others may well do so in secret.