USA vs MI

USA and MI both are nouns.

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

USA (noun)	MI (noun)
the army of the United States of America; the agency that organizes and trains soldiers for land warfare	the government agency in the United Kingdom that is responsible for internal security and counterintelligence on British territory
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	the government agency in the United Kingdom that is responsible for internal security and counterintelligence overseas
	a midwestern state in north central United States in the Great Lakes region, with capital Lansing
	destruction of heart tissue resulting from obstruction of the blood supply to the heart muscle