street fighter vs rival

street fighter and rival both are nouns.

Word	Noun	Adjective	Verb	Adverb
street fighter	Yes	No	No	No
rival	Yes	Yes	Yes	No

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

street fighter: a contestant who is very aggressive and willing to use underhand methods
rival: the contestant you hope to defeat

Other hypernyms of street fighter include challenger, competition, competitor, contender.

street fighter (noun)	rival (noun)
a contestant who is very aggressive and willing to use underhand methods	the contestant you hope to defeat
someone who learned to fight in the streets rather than being formally trained in the sport of boxing

street fighter (adjective)	rival (adjective)
	as a rival in a competition

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