What is the difference between referee, umpire and judge? How about the use of other similar words?
In sports like tennis, basketball, football and soccer, when do we use which?
The Wikipedia entry on referee has:
So it's really up to the terminology used by the professional / organizational bodies in each sport.
As to your second question, there is a long list, again on the Wikipedia site. For example (my emphasis):
In sports, a "referee" and an "umpire" are essentially the same thing - which term is used depends on the sport. Usually, team sports have referees, and others have umpires.
By contrast, judges in sports are the people who assign scores, and may or may not decide other scoring-related issues. For example, the referee in boxing will decide if there has been a TKO, but scores will otherwise be decided by the judges.
In legal usage, an "umpire" usually means an arbitrator who has a casting vote on a split panel of arbitrators, but who is appointed by the panel when they cannot decide unanimously (or perhaps by majority).
A referee is otherwise one who takes a reference, as under a reference procedure for dispute resolution.
A judge usually means a judicial officer appointed by the state to hear court cases. It tends to be used generically for all such appointments, and may also be a rank or designation in its own right (as in, His Honour Judge Nic Madge).