river vs Hudson River

river and Hudson River both are nouns.

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

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