purchase vs bargain

purchase and bargain both are nouns.

Word	Noun	Adjective	Verb	Adverb
purchase	Yes	No	Yes	No
bargain	Yes	No	Yes	No

As nouns, bargain is a hyponym of purchase; that is, bargain is a word with a more specific, narrower meaning than purchase:

Other hyponyms of purchase include stock buyback, buy, steal.

purchase (noun)	bargain (noun)
the acquisition of something for payment	an agreement between parties (usually arrived at after discussion) fixing obligations of each
the mechanical advantage gained by being in a position to use a lever	an advantageous purchase
a means of exerting influence or gaining advantage
something acquired by purchase

purchase (verb)	bargain (verb)
obtain by purchase; acquire by means of a financial transaction	come to terms; arrive at an agreement
	negotiate the terms of an exchange