War between the States vs American Civil War

War between the States and American Civil War both are nouns.

Word	Noun	Adjective	Verb	Adverb
War between the States	Yes	No	No	No
American Civil War	Yes	No	No	No

As nouns, War between the States and American Civil War are synonyms defined as:

War between the States and American Civil War: civil war in the United States between the North and the South; 1861-1865

Other synonyms of War between the States include United States Civil War.

War between the States (noun)	American Civil War (noun)
civil war in the United States between the North and the South; 1861-1865	civil war in the United States between the North and the South; 1861-1865