buff vs brownness

buff and brownness both are nouns.

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

As nouns, brownness is a hypernym of buff; that is, brownness is a word with a broader meaning than buff:

Other hypernyms of buff include brown.

buff (noun)	brownness (noun)
an implement consisting of soft material mounted on a block; used for polishing (as in manicuring)	an orange of low brightness and saturation
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)	brownness (adjective)
of the yellowish-beige color of buff leather

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