mainstay vs supporter

mainstay and supporter both are nouns.

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

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

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

mainstay (noun)	supporter (noun)
the forestay that braces the mainmast	a band (usually elastic) worn around the leg to hold up a stocking (or around the arm to hold up a sleeve)
a central cohesive source of support and stability	a support for the genitals worn by men engaging in strenuous exercise
a prominent supporter	a person who backs a politician or a team etc.
	a person who contributes to the fulfillment of a need or furtherance of an effort or purpose
	someone who supports or champions something