adman vs booster

adman and booster both are nouns.

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

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

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

adman (noun)	booster (noun)
someone whose business is advertising	an additional dose that makes sure the first dose was effective
	the first stage of a multistage rocket
	an amplifier for restoring the strength of a transmitted signal
	a thief who steals goods that are in a store
	someone who is an active supporter and advocate
	a person who backs a politician or a team etc.