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 world whilst is not used in American English. In British English, how ever, it is mostly used in formal contexts. It is considered literary and somewhat old fashioned by many people.