The main differences of CDMA and GSM are,
1.CDMA (Code Division Multiple Access)after digitizing data,spreads it out over the entire bandwidth available to it. GSM (Global System for Mobile communication) is a digital mobile telephone system that is widely used around the world .
2.In CDMA network,there is one physical channel and a special code for every device in the coverage network. In GSM network,every cell has a corresponding network tower, which serves the mobile phones in that cellular area.
3.Handset network service is specific in CDMA ,but in GSM it is SIM specific, User has option to select handset of his choice ,sometime it will locked with a particular network contract for a particular periods, but we can remove it by getting the unlocking service from an provider like http://www.theunlockarena.com/supported-phones/rs13wp7/
4.CDMA offers more efficient use of an analog transmission because it allows greater frequency reuse, as well as increasing battery life, improving the rate of dropped calls, and offering far greater security than GSM/TDMA. GSM is the dominant technology used around the globe and is available in more than 100 countries. It is the standard for communication for most of Asia and Europe.
5.GSM is a very straight forward standard, whereas, CDMA is somewhat complicated.