I know that this might come across as ignorant but what is the difference between Great Brittain and England?
The simple answer is Great Britain is the island that the states of England, Wales, and Scotland lie on. When one refers to Great Britain they are referring to those three states as a whole. The "United Kingdom" includes all those states and the state of Northern Ireland, which is on the island of Ireland. England is the largest state (both in terms of land and population) in Great Britain.
I'm a bit confused why Great Britain competes as pme combined team but doesn't compete as the United Kingdom. Does Northern Ireland have their own team or do they team up with the Republic of Ireland?