The `w..h..i..l’ in `whilst’ is pronounced like the word `while’, and the final `st’ sounds like the `st’ in `stupid’ and `stump’. As far as the meaning is concerned, there is no difference between `while’ and `whilst’. According to some scholars, `while’ is a much older word than `whilst’. The word `whilst’ is not used in American English; in British English, however, it is mostly used in formal contexts. It is considered literary and somewhat old fashioned by many people.