bargain vs purchase

bargain and purchase both are nouns.

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

As nouns, purchase is a hypernym of bargain; that is, purchase is a word with a broader meaning than bargain:

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

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