Here is what I read about the different technologies:
GPRS / EDGE Internet : All the phones on ImportGSM have GPRS (General Packet Radio Service). GPRS allows a cell phone to transmit data, such as web pages, ringtones, graphics, games and more. If you've ever browsed the web on your phone, you've been using GPRS to do so- unless you have EDGE. EDGE (Enhanced Data Rates for Global Evolution) is just like GPRS, but 3 times faster. EDGE allows for data rates as high as 177.6 Kbps.
3G / UMTS : 3G, or UMTS, is a Universal Mobile Telecommunications System, which takes cellular data transmission to a whole new level. Capable of sending and receiving at up to 2Mbps, UMTS is currently being used in Europe for 2 way video calls, streaming video, high speed internet and more. The USA will not see UMTS, but will be using HSDPA (High Speed Downlink Packet Access) technology, which will allow for downloads as high as 14.4 Mbps (and 5.8 Mbps uplink).
• speeds of up to 2.4576 Mb/s with Rev. 0 and up to 3.1 Mb/s with Rev. A
• EDGE can carry data speeds up to 236.8 kbit/s (nominal 177.6.kbps) for 4 timeslots (theoretical maximum is 473.6 kbit/s for 8 timeslots)
EV-DO is x10.4 faster than EDGE