The difference between Britain and England lies in their different meanings, usages, geographical locations and affiliation.

Lexically, Britain means "Britain" and England means "England". In usage, British can be used for adverbial clauses, and British can be used for adverbial clauses and attributive clauses. Geographically, Britain is the largest island in Europe, and England is an island country in the west of Europe. From the affiliation, Britain is the full name of Britain, and England belongs to a region of Britain.