Irtish vs river

Irtish and river both are nouns.

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

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