buff vs brony

buff and brony both are nouns.

Word	Noun	Adjective	Verb	Adverb
buff	Yes	Yes	Yes	No
brony	Yes	No	No	No

As nouns, brony is a hyponym of buff; that is, brony is a word with a more specific, narrower meaning than buff:

buff (noun)	brony (noun)
an implement consisting of soft material mounted on a block; used for polishing (as in manicuring)	an adult, male fan of the show My Little Pony: Friendship is Magic
a medium to dark tan color
bare skin
an ardent follower and admirer
a soft thick undyed leather from the skins of e.g. buffalo or oxen

buff (adjective)	brony (adjective)
of the yellowish-beige color of buff leather

buff (verb)	brony (verb)
polish and make shiny
strike, beat repeatedly