Little Sioux River vs river

Little Sioux River and river both are nouns.

Word	Noun	Adjective	Verb	Adverb
Little Sioux River	Yes	No	No	No
river	Yes	No	No	No

Little Sioux River (noun)	river (noun)
a river that rises in southwestern Minnesota and flows southwestward to the Missouri River in western Iowa	a large natural stream of water (larger than a creek)