Game on, but is it Team UK or Team GB?

"Why is the British Olympic team called Team GB and not Team UK?", my son asked me. "What's the difference between the United Kingdom and Great Britain? Is Britain the same as Great Britain? Why is the UK a country when it is a union of countries? So, is England a country?"

If you are as clueless as I was, don't worry! I heard it can be very confusing even for the average Brit! I have asked many British pallies the difference between the UK, GB and Britain but could never get a straight answer.

Wikipedia says
"The United Kingdom of Great Britain and Northern Ireland[nb 5] (commonly known as the United Kingdom (UK) or Britain) is a sovereign state located off the north-western coast of continental Europe. The country includes the island of Great Britain, the north-eastern part of the island of Ireland and many smaller islands. Northern Ireland is the only part of the UK that shares a land border with another sovereign state—the Republic of Ireland. Apart from this land border the UK is surrounded by the Atlantic Ocean, the North Sea, the English Channel and the Irish Sea."

Did that get your head spinning? Hello, someone please explain to me in kindergarten terms!

Then, I found this pictorial representation in a website for Woodlands Junior School.

Finally, a clear explanation! It got me straight in a flash!

Countries within a Country - The United Kingdom
The name United Kingdom refers to the union of what were once four separate countries: England, Scotland, Wales and Ireland (though most of Ireland is now independent, only Northern Ireland remains part of the UK).

The United Kingdom

The UK's full and official name is the "United Kingdom of Great Britain and Northern Ireland".

Great Britain
Great Britain comprises only England, Scotland and Wales.

Britain
Britain comprises England and Wales and does not include Scotland.

Hope that helped! You are welcome!

Back to my first question - so is it Team UK or Team GB?

According to Wikipedia
Great Britain was the name assigned to the United Kingdom team by the International Olympic Committee[citation needed] for the 1908 Summer Olympics along with the IOC country code GBR. The team is also referred to as Team GB.[4] Representatives of the devolved Northern Ireland government, however, have objected to the name, which they argue creates a perception that Northern Ireland is not part of the British Olympic team, and have called for the team to be renamed as Team UK.[3][6]
Under the terms of a long-standing settlement between the British Olympic Association and the Olympic Council of Ireland,[citation needed] athletes from Northern Ireland can elect to represent Ireland at the Olympics, as Northern Irish people are legally entitled to dual citizenship.[7]

But I still see Team GB on all the Olympics Merchandise at the malls.

British pallies! I'd love your answer.