adman vs promoter

adman and promoter both are nouns.

Word	Noun	Adjective	Verb	Adverb
adman	Yes	No	No	No
promoter	Yes	No	No	No

As nouns, promoter is a hyponym of adman; that is, promoter is a word with a more specific, narrower meaning than adman:

Other hyponyms of adman include huckster, booster, plugger, tout, touter.

adman (noun)	promoter (noun)
someone whose business is advertising	someone who is an active supporter and advocate
	a sponsor who books and stages public entertainments