Bluetooth versus WiFi
Bluetooth and wifi serve very different purposes.

Bluetooth is designed for connecting peripherals to computers at short range (&lt;10M) and moderate data rates. It aims to minimize power consumption. Think of it as wireless USB.

Wifi is designed for connecting computers to networks at moderate range (5-50M) and high data rates. It aims to maximize range and data throughput, while not being unduly power intensive for computers. Think of it as wireless ethernet.