Judge, arbiter, arbitrator, referee, umpire are comparable when they denote a person who decides or helps to decide questions or issues that are unsettled or in controversy.
Judge implies the assumption or the possession both of superior knowledge, experience, or wisdom, and of the power to determine the truth by weighing critically and impartially the merits of a case.
Arbiter stresses authoritativeness of decision and is applied to one, whether or not a professed judge, whose word or example is accepted as final and indisputable.
Arbitrator, referee, and umpire are applied to persons to whom a dispute is referred for decision.
Arbitrator, though sometimes interchangeable with arbiter, usually is applied to a person chosen by the parties to a controversy or appointed under statutory authority to resolve the differences between the parties and to formulate a fair solution.
In legal use referee is applied to an attorney-at-law appointed either to determine a case or to report on it to the court which he serves as an officer. It is therefore clearly distinguishable from arbitrator.
Umpire, on the other hand, is applied to the person selected to make a final decision when arbitrators have disagreed or are tied. In sports and games both umpire and referee are technical terms applied to the official or officials charged with the regulation and supervision of a contest (as by enforcement of rules of a game, making decisions on plays, and determining penalties for faults).
In most sports either one term or the other is used; thus, these officials in baseball, cricket, and tennis are designated umpires, while in boxing, basketball, football, and ice hockey they are designated referees. In nontechnical use referee usually is applied to one to whom disputants have recourse when agreement seems impossible, umpire to one who enters in and arbitrarily ends the struggle or dispute.