Speed depends on many factors, most of which are outside your control. Some are: the device (EDGE or 3G), the processor, memory, the connection, distance to the tower, tower congestion and couple others.
Speeds vary because of the above, but generally, EDGE is 50-125 kbps with a max of 384 kbps. 3G/EVDO is 400-900 kbps with a max up to about 3.5 mbps.
In your case you are comparing apples to oranges as the devices are not side by side and connecting to the same sites.