river vs Irrawaddy River

river and Irrawaddy River both are nouns.

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

river (noun)	Irrawaddy River (noun)
a large natural stream of water (larger than a creek)	the main river of Myanmar rising in the north and flowing south through the length of Burma to empty into the Andaman Sea