important vs great

important is not a noun while great is a noun.

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

important (noun)	great (noun)
	a person who has achieved distinction and honor in some field

important (adjective)	great (adjective)
of great significance or value	excellent
of extreme importance; vital to the resolution of a crisis	in an advanced stage of pregnancy
important in effect or meaning	uppercase
having or suggesting a consciousness of high position	remarkable or out of the ordinary in degree or magnitude or effect
having authority or ascendancy or influence	of major significance or importance
	relatively large in size or number or extent; larger than others of its kind