Cocytus vs River Cocytus

Cocytus and River Cocytus both are nouns.

Word	Noun	Adjective	Verb	Adverb
Cocytus	Yes	No	No	No
River Cocytus	Yes	No	No	No

As nouns, Cocytus and River Cocytus are synonyms defined as:

Cocytus and River Cocytus: (Greek mythology) a river in Hades that was said to be a tributary of the Acheron

Cocytus (noun)	River Cocytus (noun)
(Greek mythology) a river in Hades that was said to be a tributary of the Acheron	(Greek mythology) a river in Hades that was said to be a tributary of the Acheron