significance vs important

significance is a noun but important is not a noun.

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

significance (noun)	important (noun)
the quality of being significant
a meaning that is not expressly stated but can be inferred
the message that is intended or expressed or signified

significance (adjective)	important (adjective)
	of great significance or value
	of extreme importance; vital to the resolution of a crisis
	important in effect or meaning
	having or suggesting a consciousness of high position
	having authority or ascendancy or influence