Milk River vs Milk

Milk River and Milk both are nouns.

Word	Noun	Adjective	Verb	Adverb
Milk River	Yes	No	No	No
Milk	Yes	No	No	No

As nouns, Milk River and Milk are synonyms defined as:

Milk River and Milk: a river that rises in the Rockies in northwestern Montana and flows eastward to become a tributary of the Missouri River

Milk River (noun)	Milk (noun)
a river that rises in the Rockies in northwestern Montana and flows eastward to become a tributary of the Missouri River	a river that rises in the Rockies in northwestern Montana and flows eastward to become a tributary of the Missouri River