St. John River vs Saint John River

St. John River and Saint John River both are nouns.

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

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

St. John River and Saint John River: a river that rises in Maine and flows northeastward through New Brunswick to empty into the Bay of Fundy

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

St. John River (noun)	Saint John River (noun)
a river that rises in Maine and flows northeastward through New Brunswick to empty into the Bay of Fundy	a river that rises in Maine and flows northeastward through New Brunswick to empty into the Bay of Fundy