bibliopolist vs bargainer

bibliopolist and bargainer both are nouns.

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

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

bibliopolist: a dealer in secondhand books (especially rare or curious books)
bargainer: someone who purchases and maintains an inventory of goods to be sold

Other hypernyms of bibliopolist include dealer, monger, trader.

bibliopolist (noun)	bargainer (noun)
a dealer in secondhand books (especially rare or curious books)	someone who purchases and maintains an inventory of goods to be sold
	negotiator of the terms of a transaction