river vs River Clyde

river and River Clyde both are nouns.

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

river (noun)	River Clyde (noun)
a large natural stream of water (larger than a creek)	a river in western Scotland that flows from the southern uplands into the Firth of Clyde; navigable by oceangoing vessels as far as Glasgow