river vs Vistula River

river and Vistula River both are nouns.

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

river (noun)	Vistula River (noun)
a large natural stream of water (larger than a creek)	the longest and largest river in Poland; flows into the Baltic Sea