Northerner vs Federal

Northerner and Federal both are nouns.

Word	Noun	Adjective	Verb	Adverb
Northerner	Yes	No	No	No
Federal	Yes	Yes	No	No

As nouns, Federal is a hyponym of Northerner; that is, Federal is a word with a more specific, narrower meaning than Northerner:

Northerner: an American who lives in the North (especially during the American Civil War)
Federal: a member of the Union Army during the American Civil War

Other hyponyms of Northerner include Federal soldier, Union soldier.

Northerner (noun)	Federal (noun)
an inhabitant of the North	any federal law-enforcement officer
an American who lives in the North (especially during the American Civil War)	a member of the Union Army during the American Civil War

Northerner (adjective)	Federal (adjective)
	being of or having to do with the northern United States and those loyal to the Union during the American Civil War