Great Britain vs High Commission

Great Britain and High Commission both are nouns.

Word	Noun	Adjective	Verb	Adverb
Great Britain	Yes	No	No	No
High Commission	Yes	No	No	No

Great Britain (noun)	High Commission (noun)
an island comprising England and Scotland and Wales	an embassy of one British Commonwealth country to another
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