Briton vs Great Britain

Briton and Great Britain both are nouns.

Word	Noun	Adjective	Verb	Adverb
Briton	Yes	Yes	No	No
Great Britain	Yes	No	No	No

Briton (noun)	Great Britain (noun)
an inhabitant of southern Britain prior to the Anglo-Saxon invasions	an island comprising England and Scotland and Wales
a native or inhabitant of Great Britain	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

Briton (adjective)	Great Britain (adjective)
characteristic of or associated with the Britons