如何区分英国和大不列颠 How to Understand the Difference Between the UK and Great Britain
A: So where are you from?
B: Scotland. Are you Scottish too?
A: Well no, I'm English actually, but...you know...it's all like the same thing, isn't it?
B: Not exactly.
A: Go on! Isn't Scotland just like…well…a bit of England?
B: No, it is not!
A: Sorry, Britain I mean.
B: “Britain” is not “England.” 
A: Well yeah…I know that, I'm not stupid or anything. But Britain's like England, Scotland and Wales, isn't it?
B: Not exactly.
A: Yeah, it is the UK—the United Kingdom.
B: The United Kingdom is Scotland, England, Wales and Northern Ireland.
A: Oh I see, but we're all like the same nation, aren't we?
B: Not really. Four nations, one state.
A: Oh, I get it. So the UK is like the same as Great Britain.
B: Great Britain is a geographical term—it's a big island with Scotland, England and Wales on it.
A: Oh right, but we all have the same prime minister, don't we?
B: Yes. And the same head of state.
A: The Queen!
B: Exactly.
A: And the same government?
B: Well, Scotland, Wales and Northern Ireland have their own local parliaments[国会].
A: Oh. I see.
B: It's complicated.
A: Yeah, I can see that.
相关知识
英国（United Kingdom，UK）全称大不列颠及北爱尔兰联合王国（the United Kingdom of Great Britain and Northern Ireland），是由大不列颠岛（包括英格兰England、苏格兰Scotland、威尔士Wales）、 爱尔兰岛东北部（北爱尔兰Northern Ireland）和一些小岛组成，一统于一个中央政府和国家元首。首都在英格兰首府伦敦，主体还是英格兰，所以习惯上称英国（本来英国专指 英格兰）。英国本土位于大不列颠群岛，被北海、英吉利海峡、凯尔特海、爱尔兰海和大西洋包围。国土面积24.41万平方公里（包括内陆水域），人口约6140万。
大不列颠岛（Great Britain）是世界第九大、欧洲最大岛屿，面积为24万平方公里，是大不列颠及北爱尔兰联合王国国土的主要部分，由英格兰、苏格兰及威尔士组成，这三个王国即占该岛的全部。英格兰位于大不列颠岛的西南方，苏格兰以南、威尔士以东，是英国面积最大、人口最多、经济最发达的一个部分，历史上跟苏格兰以哈德里安城墙为界。
大不列颠岛是不列颠群岛（British Isles）中的第一大岛，周围环绕着超过1000座小型岛屿，该岛全境目前都为联合王国领土。