Great Britain vs life office

Great Britain and life office both are nouns.

Word	Noun	Adjective	Verb	Adverb
Great Britain	Yes	No	No	No
life office	Yes	No	No	No

Great Britain (noun)	life office (noun)
an island comprising England and Scotland and Wales	life assurance office
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