USA vs Sunbelt

USA and Sunbelt both are nouns.

Word	Noun	Adjective	Verb	Adverb
USA	Yes	No	No	No
Sunbelt	Yes	No	No	No

USA (noun)	Sunbelt (noun)
the army of the United States of America; the agency that organizes and trains soldiers for land warfare	states in the south and southwest that have a warm climate and tend to be politically conservative
North American republic containing 50 states - 48 conterminous states in North America plus Alaska in northwest North America and the Hawaiian Islands in the Pacific Ocean; achieved independence in 1776