U.S.A. vs merica

U.S.A. and merica both are nouns.

Word	Noun	Adjective	Verb	Adverb
U.S.A.	Yes	No	No	No
merica	Yes	No	No	No

As nouns, merica is a hyponym of U.S.A.; that is, merica is a word with a more specific, narrower meaning than U.S.A.:

U.S.A.: 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
merica: A pejorative term for the United States

U.S.A. (noun)	merica (noun)
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	A pejorative term for the United States