bargainer vs barrow-man

bargainer and barrow-man both are nouns.

Word	Noun	Adjective	Verb	Adverb
bargainer	Yes	No	No	No
barrow-man	Yes	No	No	No

As nouns, barrow-man is a hyponym of bargainer; that is, barrow-man is a word with a more specific, narrower meaning than bargainer:

bargainer: someone who purchases and maintains an inventory of goods to be sold
barrow-man: a hawker of fruit and vegetables from a barrow

bargainer (noun)	barrow-man (noun)
someone who purchases and maintains an inventory of goods to be sold	a hawker of fruit and vegetables from a barrow
negotiator of the terms of a transaction