Sour Skittles in America are different from the Sour Skittles in Britain. I'm British and I went to America and found out the sour skittles in America are more sour and have got sugar on the coating.. They're stickier. The British Sours are like the normal but diff colours and flavours.
Personally, I prefer the British Sour, as some of the American sours were REALLY sour. They're all nice though!