important vs operative

important is not a noun while operative is a noun.

Word	Noun	Adjective	Verb	Adverb
important	No	Yes	No	No
operative	Yes	Yes	No	No

important (noun)	operative (noun)
	someone who can be employed as a detective to collect information and assist in criminal investigations
	a person secretly employed in espionage for a government

important (adjective)	operative (adjective)
of great significance or value	being in force or having or exerting force
of extreme importance; vital to the resolution of a crisis	relating to or requiring or amenable to treatment by surgery especially as opposed to medicine
important in effect or meaning	(of e.g. a machine) performing or capable of performing
having or suggesting a consciousness of high position	effective; producing a desired effect
having authority or ascendancy or influence