Bluetooth Low Energy is a feature of Bluetooth 4.0
Starting 2011, you will see some devices using bluetooth low energy wireless technology in the market. Bluetooth Core Specification version 4.0 is a dual mode which includes both classic bluetooth and bluetooth low energy. This version aimed at new low-power and low-latency for wireless devices like battery operated sensor types of applications. While Bluetooth 2.1 and 3.0HS introduced a higher data rate functionality. Low-energy Bluetooth is now applied to connect low-power devices such as, watches, remote control and sensors.