The main differences I found are the next: Type of storage used: GSM (SIM Card) CDMA (Internal Memory). Network Service: GSM (Dictated by the user’s SIM card) CDMA (Dictated by the user’s device). International Ro, aming: GSM (Easier access) CDMA (More difficult access). Frequency band: GSM (Multiple: 850, 900, 1800, and 1900 MHz) CDMA (Single: 850 MHz). Data Transfer: GSM (GPRS/E/3G/4G/LTE) CDMA (EVDO/3G/4G/LTE).