United Kingdom of Great Britain and Northern Ireland vs British Isles

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

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

United Kingdom of Great Britain and Northern Ireland (noun)	British Isles (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	Great Britain and Ireland and adjacent islands in the north Atlantic