mainstay vs champion

mainstay and champion both are nouns.

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

As nouns, champion is a hypernym of mainstay; that is, champion is a word with a broader meaning than mainstay:

Other hypernyms of mainstay include admirer, booster, friend, protagonist, supporter.

mainstay (noun)	champion (noun)
the forestay that braces the mainmast	someone who fights for a cause
a central cohesive source of support and stability	someone who has won first place in a competition
a prominent supporter	a person who backs a politician or a team etc.
	someone who is dazzlingly skilled in any field

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

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