High Commission vs Great Britain

High Commission and Great Britain both are nouns.

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

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