private vs confidential

private is a noun but confidential is not a noun.

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

private (noun)	confidential (noun)
an enlisted man of the lowest rank in the Army or Marines

private (adjective)	confidential (adjective)
confined to particular persons or groups or providing privacy	the level of official classification for documents next above restricted and below secret; available only to persons authorized to see documents so classified
not expressed	denoting confidence or intimacy
concerning one person exclusively	entrusted with private information and the confidence of another
concerning things deeply private and personal	(of information) given in confidence or in secret