U.S. vs War between the States

U.S. and War between the States both are nouns.

Word	Noun	Adjective	Verb	Adverb
U.S.	Yes	No	No	No
War between the States	Yes	No	No	No

U.S. (noun)	War between the States (noun)
the executive and legislative and judicial branches of the federal government of the United States	civil war in the United States between the North and the South; 1861-1865
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