United Kingdom of Great Britain and Northern Ireland vs green paper

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

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

United Kingdom of Great Britain and Northern Ireland (noun)	green paper (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	a preliminary report of government proposals that is published in order to stimulate discussion