street fighter vs belligerent

street fighter and belligerent both are nouns.

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

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

street fighter: someone who learned to fight in the streets rather than being formally trained in the sport of boxing
belligerent: someone who fights (or is fighting)

Other hypernyms of street fighter include battler, combatant, fighter, scrapper.

street fighter (noun)	belligerent (noun)
a contestant who is very aggressive and willing to use underhand methods	someone who fights (or is fighting)
someone who learned to fight in the streets rather than being formally trained in the sport of boxing

street fighter (adjective)	belligerent (adjective)
	characteristic of an enemy or one eager to fight
	engaged in war