councilman vs councillor

councilman and councillor both are nouns.

Word	Noun	Adjective	Verb	Adverb
councilman	Yes	No	No	No
councillor	Yes	No	No	No

As nouns, councillor is a hypernym of councilman; that is, councillor is a word with a broader meaning than councilman:

Other hypernyms of councilman include council member, adult male, man.

councilman (noun)	councillor (noun)
a man who is a council member	a member of a council