Red River of the South vs Red

Red River of the South and Red both are nouns.

Word	Noun	Adjective	Verb	Adverb
Red River of the South	Yes	No	No	No
Red	Yes	No	No	No

As nouns, Red River of the South and Red are synonyms defined as:

Red River of the South and Red: a tributary of the Mississippi River that flows eastward from Texas along the southern boundary of Oklahoma and through Louisiana

Other synonyms of Red River of the South include Red River.

Red River of the South (noun)	Red (noun)
a tributary of the Mississippi River that flows eastward from Texas along the southern boundary of Oklahoma and through Louisiana	a tributary of the Mississippi River that flows eastward from Texas along the southern boundary of Oklahoma and through Louisiana