Incidentally I have heard the CBS news about the Bulgarian president visit in US. The exact sentence was something like:
We can't be too specific about the president's schedule due to security concerns which are an issue for all visiting dignitaries.
What took me by surprise was that they used the word dignitary while in Bulgarian recently we tend to use the foreign word VIP for that no matter if it is a man with a specific (official) rank in the society or a famous singer. It pretty much sum up all these occasions, so my question is: what is the difference in meaning between dignitary and VIP and when and why should we use each?