Sim Card Compatibility
The major difference between 2G,3G and 4G smart watches is driven by the watches compatibility with the respective capability of the SIM cards used in the watch. 2G SIM card compatible watches with GPRS/EDGE, data services can data transfer between 56 and 236.8 kilobits of data per second. However, 3G/4G SIM cards can transfer more than 14,400 kilobits per second. This makes 3G and 4G compatible watches better for downloading data like web pages and multimedia.
While 3G and 4G essentially provide superior data transfer rates, 4G is vastly superior to 3G in most situations. However, 4G watches drains more of your battery than 3G does and you may use more data due to the higher speeds.
Constant Internet Connection
Unlike 2G, 3G and 4G technology uses Internet Protocol (IP) connectivity which is packet-based. This means that using devices with a 3G or 4G capability are always connected to the Internet.
2G smart watches do not have operating system whose functions are fixed in designing period, and provide little space for user expansion.
3G and 4G smart watch have their own operating system, CPU, storage and software. Users can download APPS by connecting Wi-Fi or cellular data.