Mid-Atlantic states vs U.S.

Mid-Atlantic states and U.S. both are nouns.

Word	Noun	Adjective	Verb	Adverb
Mid-Atlantic states	Yes	No	No	No
U.S.	Yes	No	No	No

Mid-Atlantic states (noun)	U.S. (noun)
a region of the eastern United States comprising New York and New Jersey and Pennsylvania and Delaware and Maryland	the executive and legislative and judicial branches of the federal government of the United States
	North American republic containing 50 states - 48 conterminous states in North America plus Alaska in northwest North America and the Hawaiian Islands in the Pacific Ocean; achieved independence in 1776