BLE 4.2 比 BLE4.1 多了一些新的特性。
Low-power IP (IPv6/6LoWPAN) Bluetooth Smart Internet Gateways (GATT)
https://www.semiconductorstore.com/blog/2015/BLE-4-2-vs-BLE-4-1/1548
不过 4.0 到 4.1 差别不大，硬件不需要改变。