Zigbee Vs. Bluetooth

Both run in the 2.4-GHz unlicensed frequency band, and both use small form factors and low power.
ZigBee differs from Bluetooth in many ways, but essentially it addresses a different set of market requirements. Bluetooth is more oriented toward user mobility and eliminating short-distance cabling. ZigBee aims more for grand-scale automation and remote control. ZigBee targets inexpensive, low-power applications. Integrated ZigBee chipsets, with battery power slated to last six months to two years, are available for $1 or less. In addition, ZigBee-enabled devices are networked readily, as many as 65,536 such devices can be connected in a star topology or a peer-to-peer configuration. The data rate for this cost-effective and low-power technology is 20K to 250Kbps.
Zigbee is best in cases where the Network is static, there are lots of devices, they are infrequently used, Small Data Packets. Bluetooth uses a higher data rate, higher power consumption, and works with large packet devices, it’s best for Ad-hoc networks between capable devices, Handsfree audio, Pictures, File transfer. ZigBee networks can support a larger number of devices and a longer range between devices than Bluetooth. Because of these differences, the technologies are not only geared toward different applications, they don’t have the capability to extend out to other applications. As an example, for its applications, Bluetooth must rely on fairly frequent battery recharging, while the whole goal of ZigBee is for a user to be able to put a couple of batteries in the devices and forget about them for months to years. In timing critical applications, ZigBee is designed to respond quickly, while Bluetooth takes much longer and could be detrimental to the application. Thus, a user could easily use both technologies as a wireless solution in a PAN to suit all types of applications within that network.
these two technologies do not compete as the target areas regarding the usage and the application fields are different.ZigBee is mainly focused on automation and control applications (industry,sensor networks etc),while Bluetooth targets on offering connectivity for mass user market shares (laptops, mobile phones,entertainment related devices, multimedia). Protocol specifications between the two protocols differ which result in the differentiation of their target application fields. ZigBee’s characteristics is the low data rate,offering low power consumption.On the other side Bluetooth offers higher data rate,consuming more power. ZigBee oriented networks usually include larger number of connected nodes offering longer distance in terms of connectivity than a Bluetooth network structure which usually features small number of nodes connected for limited distance. Those completely different sets of characteristics ,place the two technologies into different market positions as the type of applications that each one is applied for do not share the same requirements.