buff vs tegument

buff and tegument both are nouns.

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

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

Other hypernyms of buff include cutis, skin.

buff (noun)	tegument (noun)
an implement consisting of soft material mounted on a block; used for polishing (as in manicuring)	a natural protective body covering and site of the sense of touch
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)	tegument (adjective)
of the yellowish-beige color of buff leather

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