arbiter vs arbitrator

arbiter and arbitrator both are nouns.

Word	Noun	Adjective	Verb	Adverb
arbiter	Yes	No	No	No
arbitrator	Yes	No	No	No

As nouns, arbiter and arbitrator are synonyms defined as:

arbiter and arbitrator: someone chosen to judge and decide a disputed issue

Other synonyms of arbiter include umpire.

arbiter (noun)	arbitrator (noun)
someone chosen to judge and decide a disputed issue	someone chosen to judge and decide a disputed issue
someone with the power to settle matters at will