harmonizer vs intermediary

harmonizer and intermediary both are nouns.

Word	Noun	Adjective	Verb	Adverb
harmonizer	Yes	No	No	No
intermediary	Yes	No	No	No

As nouns, intermediary is a hypernym of harmonizer; that is, intermediary is a word with a broader meaning than harmonizer:

harmonizer: a mediator who brings one thing into harmonious agreement with another
intermediary: a negotiator who acts as a link between parties

Other hypernyms of harmonizer include go-between, intercessor, intermediator, mediator.

harmonizer (noun)	intermediary (noun)
a mediator who brings one thing into harmonious agreement with another	a negotiator who acts as a link between parties
a musician who sings or plays in harmony