United Mexican States vs Rio Grande

United Mexican States and Rio Grande both are nouns.

Word	Noun	Adjective	Verb	Adverb
United Mexican States	Yes	No	No	No
Rio Grande	Yes	No	No	No

United Mexican States (noun)	Rio Grande (noun)
a republic in southern North America; became independent from Spain in 1810	a North American river; boundary between the United States and Mexico; flows into Gulf of Mexico