Transcript of the video.

     If you get confused when you use these titles, know that you’re in good company.

Britain and Great Britain are used interchangeably and mean the union of England, Scotland, and Wales.

The United Kingdom (full title: The United Kingdom of Great Britain and Northern Ireland, abbreviated to the UK) comprises England, Scotland, Wales, and Northern Ireland.

The British Isles are a group of islands off the northwest coast of Europe, consisting of Great Britain (England, Wales, and Scotland), Ireland, and adjacent islands.

Ireland (referred to as The Republic of Ireland) is an independent sovereign state. Source: Hardcover Longman, Online Cambridge, Collins, and The Hutchinson Encyclopedia