errr not really mate.
edge is an enhanced version of gprs and therefore can provide a much faster data connection. i quote from wikipedia "EDGE/EGPRS is a superset to GPRS and can function on any network with GPRS deployed on it, provided the carrier implements the necessary upgrade".
edge availability is noted with an 'E' inside the blue box whilst gprs is merely a blue box.
however, there has always been debates about this; sometimes your phone might show an edge coverage but ironically it can be slower than grps. thats because the speed is highly dependent on signal strength and of course the network provider (hence we can observe that digi's edge is way better than maxis)
hope this clears all the confusion.