western United States vs U.S.A.

western United States and U.S.A. both are nouns.

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

western United States (noun)	U.S.A. (noun)
the region of the United States lying to the west of the Mississippi River	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