river vs Rappahannock River

river and Rappahannock River both are nouns.

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

river (noun)	Rappahannock River (noun)
a large natural stream of water (larger than a creek)	a river that flows across eastern Virginia into the Tidewater region