MI vs United Kingdom of Great Britain and Northern Ireland

MI and United Kingdom of Great Britain and Northern Ireland both are nouns.

Word	Noun	Adjective	Verb	Adverb
MI	Yes	No	No	No
United Kingdom of Great Britain and Northern Ireland	Yes	No	No	No

MI (noun)	United Kingdom of Great Britain and Northern Ireland (noun)
the government agency in the United Kingdom that is responsible for internal security and counterintelligence on British territory	a monarchy in northwestern Europe occupying most of the British Isles; divided into England and Scotland and Wales and Northern Ireland; `Great Britain' is often used loosely to refer to the United Kingdom
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