river vs Brazos River

river and Brazos River both are nouns.

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

river (noun)	Brazos River (noun)
a large natural stream of water (larger than a creek)	a river that rises in Mexico and flows across Texas into the Gulf of Mexico