extensive vs intensive

extensive is not a noun while intensive is a noun.

Word	Noun	Adjective	Verb	Adverb
extensive	No	Yes	No	No
intensive	Yes	Yes	No	No

extensive (noun)	intensive (noun)
	a modifier that has little meaning except to intensify the meaning it modifies

extensive (adjective)	intensive (adjective)
of agriculture; increasing productivity by using large areas with minimal outlay and labor	of agriculture; intended to increase productivity of a fixed area by expending more capital and labor
broad in scope or content	tending to give force or emphasis
large in spatial extent or range or scope or quantity	characterized by a high degree or intensity; often used as a combining form