Please pardon my ignorance, but what is the difference between England and Britain? I thought they were the same, but they each have their own word. Of course the United States is often also called America (though erroneously I think). Is England the country and Britain the island??
For a full explanation, see the Wikipedia article 'Terminology of the British Isles'
'Britain' is sometimes used to describe the United Kingdom (Wales, Scotland, Northern Ireland and England), and sometimes to describe the geographical area excluding the island of Ireland. Sometimes it is used to describe its historical extent, such as 'Roman Britain'.
England is one of the political and geographical countries within the UK.
Note also that 'Great Britain' is just the big island of England/Wales/Scotland, and does not include either part of Ireland, but 'British Isles' does (along with the Isle of Man). 'Great' refers to its size, to distinguish it from Brittany in northern France (settled in the post-roman period by British refugees fleeing the Saxons).
Never make the mistake of telling a Welshman/woman that Wales is part of England. Just don't.