I often use this type of diagram to show the different bodies in Europe – for example the EFTA (European Free Trade Association), EEA (European Economic Area), and EU countries.
Many of my students also have trouble distinguishing between the UK and Britain, England and Britain, and use Ireland to mean the Republic of Ireland.
Thanks for this Steve!
Another one is the ‘Common Travel Area’ for UK which is England, Wales, Scotland, the Channel Islands, Isle of Man, Northern Ireland and Ireland (Southern Ireland)
https://en.wikipedia.org/wiki/Common_Travel_Area