rival vs contender

rival and contender both are nouns.

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

As nouns, rival and contender are synonyms defined as:

Other synonyms of rival include challenger, competition, competitor.

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

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

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