Same thing, different extension. :) DOS has traditionally only allowed 3-digit extensions. These days however, there are so few DOS-based systems floating around that you can more or less have any extension you like. However, there is a counterpoint. Windows uses the extension to detrmine the mimetype of a file, so the extension does still matter on those systems. 'jpeg' is still an acceptible extension though. Linux, Unix, Mac, and other systems determine the mimetype by looking at the content rather than the extension, so it doesn't matter nearly as much on those systems. A filename extension, if any, would only be superficial and for the benefit of the user.
-AT