Hudson River vs river

Hudson River and river both are nouns.

Word	Noun	Adjective	Verb	Adverb
Hudson River	Yes	No	No	No
river	Yes	No	No	No

Hudson River (noun)	river (noun)
a New York river; flows southward into New York Bay; explored by Henry Hudson early in the 17th century	a large natural stream of water (larger than a creek)