Referees and umpires refer to law enforcers who enforce rules and settle disputes.

A referee, especially one appointed as a referee in a baseball game.

Referees refer to referees of basketball, football, hockey, rugby, billiards, boxing and wrestling.

2) Legally:

An umpire refers to a person who is appointed to solve a problem that an arbitrator fails to solve.

A referee is a lawyer appointed by the court to make a judgment on a case or make an investigation report.