classified vs confidential

classified is a noun but confidential is not a noun.

Word	Noun	Adjective	Verb	Adverb
classified	Yes	Yes	No	No
confidential	No	Yes	No	No

classified (noun)	confidential (noun)
a short ad in a newspaper or magazine (usually in small print) and appearing along with other ads of the same type

classified (adjective)	confidential (adjective)
arranged into classes	the level of official classification for documents next above restricted and below secret; available only to persons authorized to see documents so classified
official classification of information or documents; withheld from general circulation	denoting confidence or intimacy
	entrusted with private information and the confidence of another
	(of information) given in confidence or in secret