river vs Saint Johns River

river and Saint Johns River both are nouns.

Word	Noun	Adjective	Verb	Adverb
river	Yes	No	No	No
Saint Johns River	Yes	No	No	No

river (noun)	Saint Johns River (noun)
a large natural stream of water (larger than a creek)	a river in northeastern Florida that flows northward to Jacksonville and then eastward to empty into the Atlantic Ocean