moderator vs mediator

moderator and mediator both are nouns.

Word	Noun	Adjective	Verb	Adverb
moderator	Yes	No	No	No
mediator	Yes	No	No	No

As nouns, mediator is a hypernym of moderator; that is, mediator is a word with a broader meaning than moderator:

Other hypernyms of moderator include go-between, intercessor, intermediary, intermediator.

moderator (noun)	mediator (noun)
someone who mediates disputes and attempts to avoid violence	a negotiator who acts as a link between parties
someone who presides over a forum or debate
in the Presbyterian church, the officer who presides over a synod or general assembly
any substance used to slow down neutrons in nuclear reactors