fighter vs champion

fighter and champion both are nouns.

Word	Noun	Adjective	Verb	Adverb
fighter	Yes	No	No	No
champion	Yes	Yes	Yes	No

As nouns, fighter and champion are synonyms defined as:

Other synonyms of fighter include hero, paladin.

fighter (noun)	champion (noun)
a high-speed military or naval airplane designed to destroy enemy aircraft in the air	someone who fights for a cause
someone who fights (or is fighting)	someone who has won first place in a competition
someone who fights for a cause	a person who backs a politician or a team etc.
	someone who is dazzlingly skilled in any field

fighter (adjective)	champion (adjective)
	holding first place in a contest

fighter (verb)	champion (verb)
	protect or fight for as a champion