river vs Ouse River

river and Ouse River both are nouns.

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

river (noun)	Ouse River (noun)
a large natural stream of water (larger than a creek)	a river in northeastern England that flows generally southeastward to join the Trent River and form the Humber