River Clyde vs river

River Clyde and river both are nouns.

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

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