American Civil War vs War between the States

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

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

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

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

Other synonyms of American Civil War include United States Civil War.

American Civil War (noun)	War between the States (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