retroactive vs retrospective

retroactive is not a noun while retrospective is a noun.

Word	Noun	Adjective	Verb	Adverb
retroactive	No	Yes	No	No
retrospective	Yes	Yes	No	No

retroactive (noun)	retrospective (noun)
	an exhibition of a representative selection of an artist's life work

retroactive (adjective)	retrospective (adjective)
descriptive of any event or stimulus or process that has an effect on the effects of events or stimuli or process that occurred previously	concerned with or related to the past
affecting things past