21/04/16 “Difference between Great Britain, The United Kingdom, The British Isles and England”
Britain (or Great Britain) and the United Kingdom (or the UK) are both used to include England, Scotland, Wales and Northern Ireland. (Sometimes Britain or Great Britain is used just for the island which includes England, Scotland and Wales, without Northern Ireland. Irish people generally use the words Britain and British in this way.)
The British Isles is the name for England, Scotland, Wales, the whole of Ireland (which includes both Northern Ireland and the Republic of Ireland, also called “Eire”), and the smaller islands round about.
England is only one part of Britain. Scotland and Wales are not in England, and Scottish and Welsh people do not like to be called “English.”
A very informal word for a British person is Brit. Britisher is used only by non-British people; Briton is hardly used except in news reports and newspaper headlines, and to refer to the ancient inhabitants of Britain.