really vs intensive

really is not a noun while intensive is a noun.

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

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

really (adjective)	intensive (adjective)
	of agriculture; intended to increase productivity of a fixed area by expending more capital and labor
	tending to give force or emphasis
	characterized by a high degree or intensity; often used as a combining form

really (adverb)	intensive (adverb)
used to give emphasis
in fact (used as intensifiers or sentence modifiers)
in accordance with truth or fact or reality
in actual fact