Are the terms 'Great Britain' and 'the United Kingdom' synonymous?

Okay, here's the explanation: Understanding the difference between Great Britain and the United Kingdom is a common point of confusion. Geographically, Great Britain refers to the island that comprises England, Scotland, and Wales. Think of it as a single landmass. The term "United Kingdom," however, is a political term. It refers to the sovereign state officially called the United Kingdom of Great Britain and Northern Ireland. This means that in addition to England, Scotland, and Wales, the UK also includes Northern Ireland. So, while Great Britain focuses on the geographical island, the United Kingdom encompasses that island plus Northern Ireland, making it a specific political entity. This is why the terms aren't synonymous. A helpful memory aid is to remember that the "United Kingdom" is the larger group, including all of "Great Britain" plus that extra bit, Northern Ireland.
Think of 'Great Britain' as a country band that's missing one of its main members, Northern Ireland, to be considered 'the United Kingdom' super group.