Great Britain is merely the name of the largest island of the British isles, which contains the nations of England, Scotland and Wales.
The United Kingdom, is a shortened way of saying, The United Kingdom of Great Britain and Northern Ireland.
The kingdoms of England, Wales and Scotland were first united in 1603. when on the death of Elizabeth I, the Scottish King James VI, as the nearest blood relative became king of England and Wales as well (James I, of England). Though England and Scotland both retained their own parliaments.
It wasn't until 1707 that both the Scottish and English parliaments voted to merge into a single parliament at Westminster, this became known as the parliament of the United kingdom of Great Britain.
In 1800 this became the United Kingdom of Great Britain and Ireland, when Ireland was added to the union, only for it to become the United Kingdom of Great Britain and Northern Ireland, when southern Ireland left the Union in 1921.
Therefore since 1707 it has been incorrect to refer to the government at Westminster as English or England.
Confused :?
don't worry about it.
It confuses us Brits as well