river vs Irtish River

river and Irtish River both are nouns.

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

river (noun)	Irtish River (noun)
a large natural stream of water (larger than a creek)	an Asian river that rises in the Altai Mountains in northern China and flows generally northwest to become a tributary of the Ob River