bargainer vs merchandiser

bargainer and merchandiser both are nouns.

Word	Noun	Adjective	Verb	Adverb
bargainer	Yes	No	No	No
merchandiser	Yes	No	No	No

As nouns, merchandiser is a hypernym of bargainer; that is, merchandiser is a word with a broader meaning than bargainer:

bargainer: someone who purchases and maintains an inventory of goods to be sold
merchandiser: a businessperson engaged in retail trade

Other hypernyms of bargainer include merchant.

bargainer (noun)	merchandiser (noun)
someone who purchases and maintains an inventory of goods to be sold	a businessperson engaged in retail trade
negotiator of the terms of a transaction