enemy vs rival

enemy and rival both are nouns.

Word	Noun	Adjective	Verb	Adverb
enemy	Yes	No	No	No
rival	Yes	Yes	Yes	No

As nouns, rival is a hypernym of enemy; that is, rival is a word with a broader meaning than enemy:

Other hypernyms of enemy include challenger, competition, competitor, contender.

enemy (noun)	rival (noun)
an opposing military force	the contestant you hope to defeat
any hostile group of people
an armed adversary (especially a member of an opposing military force)
a personal enemy

enemy (adjective)	rival (adjective)
	as a rival in a competition

enemy (verb)	rival (verb)
	be the rival of, be in competition with
	be equal to in quality or ability