It isn't. Great Britain (or Britain) is part of the United Kingdom of Great Britain and Northern Ireland, so some people might refer to Britain OR the UK and mean the same thing. London is the capital city of the UK in the same way that Washington DC is the capital city of the US.
Great Britain is not called the UK. This is a common confusion. Great Britain is the name of an island containing England, Scotland and Wales. The United Kingdom is all of Great Britain and also Northern Ireland. Northern Ireland is on the island of Ireland, so it is not part of Great Britain. So Great Britain is not the UK, just part of it, though many people think they are the same and so they use both names.
Because they are known by both names, the United Kingdom & Britain. The UK and Britain are not exactly the same Great Britain is all the countrys that we own all over the world and the UK is england, scotland, wales and northern ire land or vice versa, but still hense why they say the United Kingdom of Great Britain.
It does not have a nickname. It's just called the United Kingdom or the UK. (Sometimes it's wrongly called Britain or Great Britain.)
The UK and Britain are slightly different. Britain, or Great Britain, is comprised of England, Scotland and Wales. When Northern Ireland is added, the country then gets its full name of The United Kingdom of Great Britain and Northern Ireland.
Scotland is on an island called Great Britain. Great Britain consists of Scotland, England and Wales. Northern Ireland is not in Great Britain but it is part of the UK (the same country as Scotland)
The UK is short for United Kingdom and is alternately called Great Britain, Britain and England, but in actuality, each of these names stands for different things.
The United Kingdom of Great Britain and Northern Ireland, often just called the United Kingdom or the UK.
England has a few nicknames like Blighty, Pompey and Albion. But perhaps you mean that England, together with Wales and Scotland, is called Great Britain. Great Britain, with Northern Ireland, is the United Kingdom of Great Britain and Northern Ireland.
UK or Britain.(capitalize!)
Sometimes people mean them to be the same but Great Britain is in fact the island comprising the mainlands of Scotland, Wales and England while the United Kingdom contains all of Scotland, England, Wales and Northern Ireland.
Great Britain means England, Scotland and Wales. the UK consists of Great Britain and Northern Ireland.
London is the capital city of Britain, of Great Britain, and of the UK (United Kingdom of Great Britain and Northern Ireland). (see related question)
Yes, England is within the UK. 'UK' stands for 'The United Kingdom of Great Britain and Northern Ireland' and England forms part of Great Britain.