Basically, while is a word that functions both as a noun and as a subordinating conjunction (ex. I ate a while before you got here / I ate while you were on your way here). Whilst is a conjunction that's a synonymous to while mostly/purely used in British and Australian English and it shouldn't be used as a noun. In terms of conjunctions whilst is the more formal of the two synonyms and quite frankly isn't used much at all. Kind of like your vs thy but not really.
Last edited by blai; April 17, 2012 at 06:24 AM.
Thanks, Adam! 'Whilst' really sounds more formal.
^ and the fact that you can't use whilst as a noun. ex. "I ate a while before you got here / I ate a whilst before you got here"
So yeah, it's used in British, it's an older (like thy) word and it can't be used as a noun.