1)GSM is standard bearer of 2G technologies.
GPRS is he upgrade over the basic GSM features. It allow the mobile handset to obtain much higher data speed than what standard GSM can offers.
2)In GSM traffic and signaling follow different multi-frame structure. i.e. 51 frame MF used for signaling and 26 frame MF used for traffic.
In GPRS traffic and signaling both follow common multi-frame structure. i.e. 52 frame MF used for both signaling as well as traffic.
3)GSM used circuit switching traffic
GPRS used for packet switching traffic.
4)In GSM UE will be in two states ,i.e IDLE and READY.
In GPRS UE will be in three states , i.e IDLE, READY and STANDBY.
5)In GSM time slot is allocated both in uplink and downlink. due to these radio resource allocation is GSM is called as Symmetric
In GPRS radio resource allocation is asymmetric, for example it is possible to allocate the time slot only in downlink not in uplink when user is only downloading the file
6)In GSM location area concept is used.
In GPRS routing area concept is used.