with-it vs smart

with-it is not a noun while smart is a noun.

Word	Noun	Adjective	Verb	Adverb
with-it	No	Yes	No	No
smart	Yes	Yes	Yes	No

with-it (noun)	smart (noun)
	a kind of pain such as that caused by a wound or a burn or a sore

with-it (adjective)	smart (adjective)
in accord with the most fashionable ideas or style	showing mental alertness and calculation and resourcefulness
having the shrewd resourcefulness needed to survive in an urban environment	capable of independent and apparently intelligent action
	quick and brisk
	improperly forward or bold
	characterized by quickness and ease in learning
	painfully severe
	elegant and stylish

with-it (verb)	smart (verb)
	be the source of pain