unacknowledged vs unknown

unacknowledged is not a noun while unknown is a noun.

Word	Noun	Adjective	Verb	Adverb
unacknowledged	No	Yes	No	No
unknown	Yes	Yes	No	No

unacknowledged (noun)	unknown (noun)
	a variable whose values are solutions of an equation
	an unknown and unexplored region
	anyone who does not belong in the environment in which they are found

unacknowledged (adjective)	unknown (adjective)
not recognized or admitted	not known
not openly acknowledged	being or having an unknown or unnamed source
	not famous or acclaimed
	not known before
	not known to exist