backer vs supporter

backer and supporter both are nouns.

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

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

Other hypernyms of backer include patron, sponsor.

backer (noun)	supporter (noun)
someone who provides financial support for some venture	a band (usually elastic) worn around the leg to hold up a stocking (or around the arm to hold up a sleeve)
	a support for the genitals worn by men engaging in strenuous exercise
	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