What is the difference between England, Britain, Great Britain, the UK, the Commonwealth, and the Crown lands?

So if a Franco plaintiff spoke solely in Quebecois and the defendant spoke only English and the judge decided to hold the trial in the plaintiff’s preferred language, the whole trial could be conducted without the defendant understanding anything and hearing at the end: “Vous lui devez un million de dollars.” with no recourse? How about the reverse?

Here you are factually incorrect. This does happen, sometimes, in part because of the Tân yn Llŷn arson case in the 1930s (BBC Wales - History - Themes - Welsh language: Civil Disobedience). Nowadays, the insistence on Welsh by people whose English is excellent is usually to call attention to the eroding of language rights, as bilingualism on the part of officials is often the case on paper but not in practice.

This is only loosely accurate. All the diagrams I’ve seen such as the one in the OP fail to point out that “Great Britain” has two very distinct meanings, which you’re mixing up here.

The first meaning is that it is the name of the island which Edinburgh, Swansea, Norwich etc sit on. I think it was usually just “Britain” until the time of James VI / I. It is just a geographical term which has very little practical significance from day to day.

The second meaning is that it is the political entity which comprises Wales, England and Scotland. It is not accurate to say that it is “the island”, because there are lots of islands which are also part of those countries, especially in Scotland.

“Great Britain” does have some relevance as a single political entity, particularly as has been mentioned nowadays with Brexit. But there are some other laws or administrative practices which apply to Great Britain but not Northern Ireland, such as those relating to vehicle and driver licensing.

This glosses over the fact that the histories of Ireland and Scotland are completely different. Ireland was a de facto colony of England from the 12th century until 1801, even if England didn’t always control the entire island (the nation state of Great Britain was the ruling power from 1707 until 1801). “The Kingdom of Ireland” was something created by the English in 1542, so they could claim that it was technically a personal union even though the Irish Parliament was legally obliged to do what the English wanted.

Scotland was a completely different nation, with a different monarch, until 1603, for example forming geo-political alliances with England’s enemy France. There was a genuine personal union, that is a shared monarch between Scotland and England, between 1603 and 1707 (except when Scotland was conquered and ruled by Cromwell between 1650 and 1660). The fact that Scotland, unlike Ireland, was an independent country is demonstrated by the Bishops’ Wars in 1639/40 when the Scottish Parliament agreed for a Scottish army to successfully invade and occupy the north of England, until it was paid to leave (thus kicking off the English Civil War part of the Wars of the Three Kingdoms).

Scotland’s political independence came to an end when the English government began to worry in the early 18th century that Scotland would end the personal union and appoint another monarch who would be friendly to England’s (Catholic) enemies, so they began to threaten invasion, and threaten the personal financial interests of Scottish politicians (some of whom had been personally weakened by the failure of the private Darien scheme).

That’s a bit of a trope amongst certain groups of people, but it does not always stand up to scrutiny. People say it, totally inaccurately, about Aberdeenshire, when in fact that area is covered with Gaelic placenames, and the whole of Scotland between the midland valley and the Pentland Firth was Gaelic speaking for centuries.

The language of what’s now the south east of Scotland in medieval times was Old-Welsh and then Old-English. But every part of what’s now mainland Scotland was conquered by Gaelic speaking kings and Gaelic speaking armies, so it’s not really possible to claim Gaelic was never spoken there. And anyway you do get Gaelic placenames in the south east, such as Dumbryden or Lammermuir.

I’m not disagreeing with you, but what’s the name of the “big” island in the British Isles? The one with England, Scotland, and Wales?

The political entity is the UK; is there actually a political entity of Great Britain separate from the UK, and separate from the island itself?

No, there isn’t. Confusingly, though, it is adopted by sports organisations for UK-wide teams, as for the Olympics.

I think I answered both these questions in my post - “[Great Britain] is the name of the island which Edinburgh, Swansea, Norwich etc sit on.”

I would have been better saying “legal” than “political”, but in the context of Great Britain meaning Scotland, Wales and England, ““Great Britain” does have some relevance as a single political entity, particularly as has been mentioned nowadays with Brexit. But there are some other laws or administrative practices which apply to Great Britain but not Northern Ireland, such as those relating to vehicle and driver licensing.”

There is though - as I say I’d have been better saying “legal” rather than “political”, but Great Britain, as in Scotland+England+Wales rather than the island, does exist as a legal entity within the UK, in contexts such as Brexit (in recent years) and vehicle and driver licensing (for the last century). There may be others.

I’m really unclear of the distinction between Great Britain the island that contains England, Scotland, and Wales, versus the legal entity that comprises the three. They would seem to overlap 100%, so why not use them interchangeably?

Consider, for example, Skye. It’s an island, and so not part of the island Great Britain. But it’s also part of Scotland, and so it is also part of anything that Scotland is part of.

Yes, exactly as Chronos has said.

Great Britain the island does not “contain England, Scotland and Wales”. Nearly 20% of Scottish land is on other islands. Both England and Wales have entire counties that are separate from the island of Great Britain.