What can a Dremel tool do that a drill cannot?
An ordinary electric drill does not have the speed of the Dremel (30,000 rpm) which is the key to getting the best results from many of the accessories.  Also, the Dremel tool is much smaller and lighter than an electric drill which is very useful in many applications such as carving, etching and working with small work pieces. Dremels can be used with non-Dremel accessories such as drill bits and grinding wheels so you are not locked in. As an example, the Dremel tool is excellent for cutting screws and nails to size using the 1 inch diameter cutting wheels.  It would be very awkward to achieve the same results with an ordinary electric drill.