conscientiousness vs conscientious

conscientiousness is a noun but conscientious is not a noun.

Word	Noun	Adjective	Verb	Adverb
conscientiousness	Yes	No	No	No
conscientious	No	Yes	No	No

conscientiousness (noun)	conscientious (noun)
the quality of being in accord with the dictates of conscience
the trait of being painstaking and careful

conscientiousness (adjective)	conscientious (adjective)
	guided by or in accordance with conscience or sense of right and wrong
	characterized by extreme care and great effort