mediator vs go-between

mediator and go-between both are nouns.

Word	Noun	Adjective	Verb	Adverb
mediator	Yes	No	No	No
go-between	Yes	No	No	No

As nouns, mediator and go-between are synonyms defined as:

mediator and go-between: a negotiator who acts as a link between parties

Other synonyms of mediator include intercessor, intermediary, intermediator.

mediator (noun)	go-between (noun)
a negotiator who acts as a link between parties	a negotiator who acts as a link between parties