Question: what is the difference between mi band 3 and mi band 4?
Answer: Battery, Connectivity In terms of connectivity, Mi Band 4 offers the latest Bluetooth 5.0 and is compatible with Android 4.4 and iOS 9.0 and above smartphones. Mi Band 3 comes with a smaller 110mAh battery and has older Bluetooth 4.2 LE. It's also compatible with Android 4.4 and iOS 9.0 and above smartphones.