river vs Allegheny River

river and Allegheny River both are nouns.

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

river (noun)	Allegheny River (noun)
a large natural stream of water (larger than a creek)	a river that rises in Pennsylvania and flows north into New York and then back south through Pennsylvania again to join the Monongahela River at Pittsburgh which is the beginning of the Ohio River