river vs Upper Tunguska

river and Upper Tunguska both are nouns.

Word	Noun	Adjective	Verb	Adverb
river	Yes	No	No	No
Upper Tunguska	Yes	No	No	No

river (noun)	Upper Tunguska (noun)
a large natural stream of water (larger than a creek)	a river in southeastern Siberia that flows northwest from Lake Baikal to become a tributary of the Yenisei River