IDG Answers is a community of experts who are passionate about technology. Ask a question or answer one below.
Besides the fact that GSM phones use SIM cards, the main difference is that CDMA uses a wider spectrum than GSM, which is good in the sense that there is more coverage but worse in terms of quality. Think of it in terms of radio frequencies with CDMA being AM radio and GSM being FM. You can get AM stations pretty much anywhere but you won't get the quality stereo sound of FM.