significant vs operative

significant is not a noun while operative is a noun.

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

significant (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

significant (adjective)	operative (adjective)
important in effect or meaning	being in force or having or exerting force
too closely correlated to be attributed to chance and therefore indicating a systematic relation	relating to or requiring or amenable to treatment by surgery especially as opposed to medicine
of considerable importance, size, or worth	(of e.g. a machine) performing or capable of performing
rich in significance or implication	effective; producing a desired effect