What's difference between 2G & 3G ??

The2G has defferant technology than3G,2G use one time slot for each call but but3G use WCDMA that use all the bandwidth for all the users and the main factor is the QoS that needed for the used service (Call, Vidio call, internet....ect,) and in this case each connected user has key to fine is data.

So2G serve less users and provide only voice call service and internet in GPRS/EDGE than3G 

This is the simplest technical explanation i can give.

many differents between 2g&3g  but the main differnt  in speed and berformance

2G networks are less compatible with the functions of smart phone. The speed of data transmission in 2G network is less than 50,000 bits per sec while in 3G it can be more than 4 million bits per sec.

 3G (3erd generation of GSM) have been make possible to provide more services than2G like internet and   vidio calls .............etc2G (2nd generation of GSM )  was adding SMS and MMS services to mobile systems

in my opinion3g is an advanced form of2g which provides better band width, better speed and opens the gate for us to explore new things like mobile televesion, video conferensing and many more.

I agree with Yasir; to add historical information1G is first generation cellular phone service that was mostly pure voice on analog RF channels. At some point there was critical need for secure registration to network, more voice channels per RF carrier and data features to name a few leading to e.g. GSM2G &3G

The terms2G (second generation) and3G (third generation) describe the technology being used by a Cellular System e.g. Europe and most of Asia used to have2G technology GSM (Global System for Mobile Communication) but now they have migrated to3G technologies such as WCDMA. USA migrated to3G long time back and is now deploying4G technology called LTE (Long Term Evolution). Another4G technology that is competing with LTE is called WiMAX. WiMAX is installed in a number of countries such as Pakistan where it is a major Wireless Broadband Access technology.

Basically 2G HP will provide only voice,messaging & photographic (Video) function

whereas 3G HP will all the above with a limited degree of internet function. Also the 

speed and capacity for 3G is higher which is normaly provided by a handphone NETWORK provider.

2G (or 2-G) is short for second-generation wireless telephone technology. Second-generation 2G cellular telecom networks were commercially launched on the GSM standard in Finland by Radiolinja (now part of Elisa Oyj) in 1991.

 

3G, stands for third generation, is the third generation of wireless mobile telecommunications technology. This is based on a set of standards used for mobile devices and mobile telecommunications use services and networks that comply with the International Mobile Telecommunications-2000 (IMT-2000) specifications by the International Telecommunication Union. 3G finds application in wireless voice telephony, mobile Internet access, fixed wireless Internet access, video calls and mobile TV.

2G (or 2-G) is short for second-generation cellular technology. ... 2G has been superseded by newer technologies such as 2.5G, 2.75G, 3G, and 4G; however, 2G networks are still used in most parts of the world.

2G-->GSM

3G-->UMTS

So the3G can contain Data and voice together adding to thouse we can have internet in high level of speed, but the2G only voice is allowed or sms/mms.

3G is better than 2G because :

1-providing faster communicationsed/recieve large emailhigh speed weblarge capacities and broadband capacities