What is Britain?
Is it the same as the UK?
What is Briton?
Wtf is up with Canada?
Is it it’s own country?
If yes, then why do they still salute the queen or king?
If no, how are they operating as it’s own country?
Same for Australia I guess, too?
Was there an Australian revolution?
Are all parts of the British island the same country?
Or are Scotland and Ireland seperate countries?
I’ll take a cursory stab, but other references exist for the minutiae of how these things came to be.
Britain == United Kingdom
Great Britain == an island wholly within the UK
United Kingdom: a sovereign state (eg USA, Germany) composed of the constituent countries of England, Scotland, Wales, and Northern Ireland, plus a few overseas territories.
Briton: a British citizen, or someone tracing their ancestry to the UK constituent countries
The short answer for why a country (UK) can have countries (eg Scotland) in it is because the notion of sovereign states (the modern definition of countries) only came into existence in the 18th century or so.
Canada, formerly the Dominion of Canada, formed from the British North American holdings plus the French parts that the British bought (ie Quebec). Granted self governance in the 1860s, independence in the 1930s, and finally full “patriation” in the 1980s to remove all vestiges of the UK from Canadian laws. However, the independent Monarchy of Canada remains, and just happens to coincidentally follow the exact same selection rules as the British Monarch. So the King of Canada will be the same person as the King of the United Kingdom, even though the Government of Canada is no longer controlled by the Government of the United Kingdom. In both sovereign states, the King is a figurehead from where authority and governmental legitimacy emanates, and the current King of Canada continues the tradition since Queen Elizabeth II that the Monarch’s appointed Governor-General of Canada shall represent the Monarch in all Canadian matters, meaning the Monarch will not directly involve themselves. In fact, it’s frowned upon for politicians to involve the Monarch directly, except to kindly ask for a new Governor-General (see 1975 Australia).
Why still keep the Monarchy of Canada? The voters haven’t chosen otherwise, to pursue a republic or any other form of government. The same applies in Australia, although it’s slightly more complicated as each Australian State derives their state-level authority from the Australian Monarch, whereas Canadian provinces exist as a part of the singular Canadian confederation; each Australian State would have to sever their connection to the Monarch, or could do so piece-meal. Nevertheless, with the Monarch delegating power within each of his “realms” to the respective Governor-General, becoming a republic is a matter of passing bills in the parliamentary system. Barbados did exactly this in 2022, replacing Queen Elizabeth II with a republic. Countries formerly part of the British Empire (circa 1930) usually join The Commonwealth of Nations, which just means they’d like to keep trading with each other but without the whole colonialism thing.
The end of the British Empire was basically slow-going, since once some parts (eg Canada) received a measure of devolved powers (like having their own parliament), the door was swung open for other parts to demand the same. Post WW2, with the status of the UK greatly diminished in deference to the USA and USSR, overseas colonies became expensive and untenable. Plus, one of the basic tenets of the United Nations – put in place to avoid yet another world war – was the right to self determination. So the colonies had to go free.
Ironically, the Scottish Parliament was not restored until 1998, having legally stopped existing with the Acts of Union 1707 that merged England and Scotland into the United Kingdom, with a single parliament but otherwise separate institutions and laws. To this day, the English Parliament has not been restored, and thus England affairs are directed by the UK Parliament at large.
The British Isles includes both the Island of Great Britain (where Wales, Scotland, and England are) plus the Island of Ireland (where the Republic of Ireland, and Northern Ireland are), and a few smaller islands. So yes, every part of Great Britain is a part of the UK sovereign state, but the UK also includes the Isle of Mann and the upper part of the Island of Ireland, and some others.
In all circumstances, “Ireland” means the Republic of Ireland; that republic is almost never called “southern Ireland”. The whole history of British colonialism in Ireland is long, sordid, and full of misery, culminating with The Troubles of the 1960s and still causing concern post-Brexit due to the EU border basically dividing the Island of Ireland.
TL;DR: everything about British history is messy. Even their former colonies have messy history, despite some being at most a few hundred years old.
For other examples of countries-in-countries, we can look to Switzerland, Germany, and the USA. A casual observation of all three are that their first-level political subdivision is known as a “state” and not “province” or “territory”.
Swiss history – which I admit I’m not that clear on – shows that the modern sovereign state formed as a loose confederation of smaller kingdoms unifying together. Indeed, the foundational document of the modern Swiss Confederation in 1848 directly drew inspiration from the USA Constitution of 1789. However, they made some modifications, such as having a 7-person Federal Council, which together fulfill the role akin to the American President. That is, the role of Head of State and also Head of Government (aka a Prime Minister). This style of executive governance hews more closely to the rich Swiss traditional of direct democracy, rather than that of a purely representative republic.
Germany, specifically the successor state of West Germany post-WW2, and then the unified state of Germany post reunification, is a federal republic. A republic to restore the functions of the earlier Weimar Republic, and a federation of states because of USA influence in drafting the Basic Law – Germany’s Constitution – following WW2. But unlike the USA federal system, the German system would mimic the parliamentary system of Westminster, being that of the United Kingdom. So while governmental power is distributed amongst the several states and the federation, the governance would be through indirect election of the Prime Minister. The idea is that by dividing power this way, no mustached fellow with fascist ideas could take control of the organs of power again.
Finally, examining the oldest continually-operating example, the USA currently is composed of a strong federal entity and 50 US States that wield all remaining power not reserved to the federal government. But initially, this is not what the American Founding Fathers had in mind at all. The late 1700s envisioned the original 13 colonies of the early United States of America to be independent countries that confederated for common causes, like defense and foreign policy. The precursor to the US Constitution – the Articles of Confederation (1777) – tried this, but problems quickly arose because each State had their own currency, debt levels, legal systems, and often undermined each other to advance their own position, such as favoring in-state citizens in lawsuits filed by out-of-state citizens. This made trade difficult and the federal government had little power to do anything about this.
Even with the revised US Constitution document, the whole weak federal government thing continued until the 1860s during the American Civil War, with the aftermath being a federal government that fully asserted its powers under the US Constitution. Any notion of US States being country-like would have fully evaporated by then, especially during Reconstruction when the Guarantee Clause was used to install military governance in the defeated southern states until reintegration into the Union. Such a thing would be impossible for a modern country/sovereign state.
Fun fact: the Guarantee Clause is why a US State cannot convert itself into a hereditary monarchy. The Constitution does not allow for a Monarchy of South Carolina, and we’re probably all better off for it anyway. Although if the role was an elected position – like with the Co-Prince of Andorra – then that might be permissible.
To that end, the modern US State is still a sovereign entity, in that certain things are wholly within their domain and not of the federal government’s. But US States are still beholden to the US Constitution, use the same money as the Union, and must honor interstate commerce and contracts from in- and out-of-state, as well as judicial rulings from the federal court system. But this dual sovereignty system post 1860s continues to evolve, with some states encroaching on federal authority, such as with border control.
Aspects of these three example countries find their way into most of the modern governments of Western countries, so hopefully this was a useful explainer.