barterer vs bargainer

barterer and bargainer both are nouns.

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

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

barterer: a trader who exchanges goods and not money
bargainer: someone who purchases and maintains an inventory of goods to be sold

Other hypernyms of barterer include dealer, monger, trader.

barterer (noun)	bargainer (noun)
a trader who exchanges goods and not money	someone who purchases and maintains an inventory of goods to be sold
	negotiator of the terms of a transaction