haggler vs bargainer

haggler and bargainer both are nouns.

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

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

haggler (noun)	bargainer (noun)
an intense bargainer	someone who purchases and maintains an inventory of goods to be sold
	negotiator of the terms of a transaction