green paper vs United Kingdom of Great Britain and Northern Ireland

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

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

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