Saint Johns River vs St. Johns

Saint Johns River and St. Johns both are nouns.

Word	Noun	Adjective	Verb	Adverb
Saint Johns River	Yes	No	No	No
St. Johns	Yes	No	No	No

As nouns, Saint Johns River and St. Johns are synonyms defined as:

Saint Johns River and St. Johns: a river in northeastern Florida that flows northward to Jacksonville and then eastward to empty into the Atlantic Ocean

Other synonyms of Saint Johns River include Saint Johns, St. Johns River.

Saint Johns River (noun)	St. Johns (noun)
a river in northeastern Florida that flows northward to Jacksonville and then eastward to empty into the Atlantic Ocean	a river in northeastern Florida that flows northward to Jacksonville and then eastward to empty into the Atlantic Ocean