slip coach vs United Kingdom of Great Britain and Northern Ireland

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

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

slip coach (noun)	United Kingdom of Great Britain and Northern Ireland (noun)
a railway car at the end of the train; it can be detached without stopping the train	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