go-between vs mediator

go-between and mediator both are nouns.

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

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

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

Other synonyms of go-between include intercessor, intermediary, intermediator.

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