a cappella vs unaccompanied

a cappella and unaccompanied both are adjectives.

Word	Noun	Adjective	Verb	Adverb
a cappella	No	Yes	No	Yes
unaccompanied	No	Yes	No	Yes

a cappella (adjective)	unaccompanied (adjective)
sung without instrumental accompaniment	being without an escort
	playing or singing without accompaniment
	(of a state or an event) taking place without something specified occurring at the same time

a cappella (adverb)	unaccompanied (adverb)
without musical accompaniment	without anybody else or anything else