What is the difference between Bluetooth 5, Bluetooth 4.2 and Bluetooth 2.0?

The Bluetooth 5.0 standard was announced in December 2016 by the Bluetooth Special interest group (SIG). Key updates to Bluetooth 5 include longer range, faster speed, and larger broadcast message capacity, as well as improved interoperability and coexistence with other wireless technologies. Bluetooth 5 will continue to advance the Internet of Things (IoT) experience by enabling simple and effortless interactions across a vast range of connected devices.

Bluetooth Low Energy (BLE) or Bluetooth Smart, is the low power version of the original Bluetooth standard. Bluetooth LE (i.e Bluetooth V4.2), provides a data rate of up to 1 Mbps while consuming just 0.01 to 0.5 watts i.e., one third of the speed of Bluetooth Classic, but while consuming half the power.