If you are uncertain whether to use while or whilst, it is always preferable to use while.
In the course of my work I read dozens of dissertations written by post-graduate students from countries far to the north of South Africa such as Malawi, Gabon, Cameroon and Nigeria. None of these students is a first-language English speaker and I have noticed that without exception they use the word whilst – never while – and this made me wonder about these two words. I have always regarded whilst as archaic, pompous, too formal and, at best, rather quaint, but none of these young men and women is any of these things.
So what is the difference? Although in British English both spellings are correct, whilst is becoming less common than it used to be – except among the educated people of Africa, apparently. American English uses while for all forms of the word. And it is advisable never to use whilst when speaking.
Not always do while and whilst mean precisely the same thing. When used as a noun while (from the Old English hwil) means ‘a period of time, usually short’ e.g. wait here for a while.
It can also be used as a verb e.g. to while away the time or as a preposition (meaning ‘until’) although this usage is archaic. It is important to note that whilst cannot be used either as a noun or a verb.
It is as a conjunction, however, that they have the same meaning and can be used interchangeably. Here they mean ‘during the time that’ e.g. watch the kettle while I leave the kitchen. Other meanings include ‘whereas’ and ‘although’ e.g. a qualified mechanic can repair the engine, while I haven’t a clue. Their use as a conjunction dates back to the 1500s.
If you are uncertain whether to use while or whilst, remember that it is always preferable to use while.