Mid-Atlantic states vs U.S.A.

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

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

Mid-Atlantic states (noun)	U.S.A. (noun)
a region of the eastern United States comprising New York and New Jersey and Pennsylvania and Delaware and Maryland	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