Red vs Red River of the South

Red and Red River of the South both are nouns.

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

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

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

Other synonyms of Red include Red River.

Red (noun)	Red River of the South (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