Mason and Dixon line vs Mason-Dixon line

Mason and Dixon line and Mason-Dixon line both are nouns.

Word	Noun	Adjective	Verb	Adverb
Mason and Dixon line	Yes	No	No	No
Mason-Dixon line	Yes	No	No	No

As nouns, Mason and Dixon line and Mason-Dixon line are synonyms defined as:

Mason and Dixon line and Mason-Dixon line: the boundary between Maryland and Pennsylvania; symbolic dividing line between North and South before the American Civil War

Other synonyms of Mason and Dixon line include Mason and Dixon's line.

Mason and Dixon line (noun)	Mason-Dixon line (noun)
the boundary between Maryland and Pennsylvania; symbolic dividing line between North and South before the American Civil War	the boundary between Maryland and Pennsylvania; symbolic dividing line between North and South before the American Civil War