United Kingdom of Great Britain and Northern Ireland vs muffin man

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

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

United Kingdom of Great Britain and Northern Ireland (noun)	muffin man (noun)
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	formerly an itinerant peddler of muffins