There's still a huge amount of confusion, not just with foreigners, but also with the citizens of this great land regarding what certain places are called. The main reason I decided to bring this up is because where the house is that I currently live in is supposedly in about 4/5 different named areas... and it causes major confusion when I try explaining it. Anyway, this isn't about me, it's about this wonderful nation/country/whatever... do we call it Britain? Great Britain? United Kingdom or the British Isles?
To save the confusion, I believe this quick Geography 101 I've made should aid confusion.
Here are the countries/regions(/whatever you want to call them):
The Channel Islands
Isle of Man
Republic of Ireland
When England and Wales are joined together, they're "technically" known as Britain
When Britain and Scotland are joined together, they're known as Great Britain (GB)
When Northern Ireland is joined with the Republic of Ireland, they're known as Ireland (or Éire)
When Northern Ireland is joined with Great Britain, it becomes the United Kingdom (UK)
When The Channel Islands, Isle of Man and the Republic of Ireland are joined with the United Kingdom, it geographically becomes the British Isles (BI)
Hope that's of some help... yeah?