northern vs North

northern is not a noun while North is a noun.

Word	Noun	Adjective	Verb	Adverb
northern	No	Yes	No	No
North	Yes	No	No	No

northern (noun)	North (noun)
	the United States (especially the northern states during the American Civil War)
	the region of the United States lying to the north of the Mason-Dixon line
	British statesman under George III whose policies led to rebellion in the American colonies (1732-1792)

northern (adjective)	North (adjective)
situated in regions of the north
in or characteristic of a region of the United States north of (approximately) the Mason-Dixon line
coming from the north; used especially of wind
oriented toward the north