Irtish vs Irtysh

Irtish and Irtysh both are nouns.

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

As nouns, Irtish and Irtysh are synonyms defined as:

Irtish and Irtysh: an Asian river that rises in the Altai Mountains in northern China and flows generally northwest to become a tributary of the Ob River

Other synonyms of Irtish include Irtish River, Irtysh River.

Irtish (noun)	Irtysh (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	an Asian river that rises in the Altai Mountains in northern China and flows generally northwest to become a tributary of the Ob River