contender vs rival

contender and rival both are nouns.

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

As nouns, contender and rival are synonyms defined as:

Other synonyms of contender include challenger, competition, competitor.

contender (noun)	rival (noun)
the contestant you hope to defeat	the contestant you hope to defeat

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

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