I know the GSM battery is listed as having 6 hrs talk time while the CDMA battery has 4 hrs talk time. Does anyone know why or what causes the different drain rate on the different networks?

Also, I know that on the GSM/GPRS networks you can be on the web and still receive a call, but on CDMA versions the call would be routed to voicemail. Are there any other operating differences between the CDMA and GSM versions?