A while and awhile are often confused due to the fact that while is often accompanied by the indefinite article. The main difference is that a while means "an amount of time" or "some duration" whereas awhile is an adverb meaning "for some amount of time" or "for some duration". Both of these sentences yield the same effective meaning. Whilst is only a conjunction, and so its use here would be incorrect.
Conjunction
The primary function of the word as a conjunction is to indicate that two separate clauses occur at the same time. While can also be legitimately used in the contrastive sense, comparable to the words "although" or "whereas", provided that it is not ambiguous : The latter sentence can mean either "during the time that Sally plays, Sue works" or "although Sally plays, Sue works" and is thus ambiguous. Fowler's Modern English Usage disapproves of several uses of the conjunctive while. At times it is inappropriately used as a coordinating conjunction: "and" or "but" should be used instead. Its usage as "elegant variation" is also discouraged, as it is masquerading as a "formal word". In some dialects of Northern England, while is translated into standard English as "until"; for example, "At least wait while we're done."
Whilst
In standard British English and Australian English, whilst, as a conjunction, is synonymous with although, whereas, but or while. Unlike whilst, while is also used as a noun or a verb. The usage of whilst is chiefly British. For example, the BBC World Service website "Learning English", in their "Ask about English" section, uses the word whilst when explaining the usage of "while and whereas". In American English, whilst is considered to be pretentious or archaic. Some publications on both sides of the Atlantic disapprove of whilst in their style guides ; for example:
The American Heritage Guide writes that, "while using whilst runs the risk of sounding pretentious, it can sometimes add a literary or ironically formal note to a piece of writing". Practical English Usage by Michael Swan, a reference book for intermediate and advanced learners of English, does not include whilst but has several sections covering the usage of while.
