base rate vs Great Britain

base rate and Great Britain both are nouns.

Word	Noun	Adjective	Verb	Adverb
base rate	Yes	No	No	No
Great Britain	Yes	No	No	No

base rate (noun)	Great Britain (noun)
the interest rate set by the Bank of England for lending to other banks	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