What is the difference between 2G and 3G ?

2G and 3G (2nd and 3rd generation mobile telecommunications technologies) refer to different generations of cellular phone standards. 2G networks (GSM, CDMAOne, D-AMPS) are the first digital cellular systems launched early 1990s. 3G networks (UMTS FDD and TDD, CDMA2000 1x EVDO, CDMA2000 3x, TD-SCDMA, Arib WCDMA, EDGE, IMT-2000 DECT) are newer cellular networks that came to the U.S. around 2003 with data rates of 384kbit/s up to 2-3 Mbits/s.

Generally, 2G offers lower data rates, and started as a voice-oriented service, while 3G offers considerably higher data rates and data oriented services.

2G uses different switching techniques for voice and data, while 3G uses single type of switching for any data. 2G is cirquit-switched (each user occupies a frequency) while 3G is packet-switched (similar to Internet data traffic). Because of that, 2G is slower, more prone to interference, and does not scale as well as 3G. 3G offers higher spectrum efficiency, asymetric uplink and downlink traffic, multiplexing of services on a single connection, variable bit rate on demand, etc.