bare-ass vs in the buff

bare-ass and in the buff both are adjectives.

Word	Noun	Adjective	Verb	Adverb
bare-ass	No	Yes	No	No
in the buff	No	Yes	No	No

As adjectives, bare-ass and in the buff are synonyms defined as:

Other synonyms of bare-ass include bare-assed, in the altogether, in the raw, naked as a jaybird, peeled, raw, stark naked.

bare-ass (adjective)	in the buff (adjective)
(used informally) completely unclothed	(used informally) completely unclothed