midwestern United States vs U.S.

midwestern United States and U.S. both are nouns.

Word	Noun	Adjective	Verb	Adverb
midwestern United States	Yes	No	No	No
U.S.	Yes	No	No	No

midwestern United States (noun)	U.S. (noun)
the north central region of the United States (sometimes called the heartland or the breadbasket of America)	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