There are no significant changes, as long as you use features that was already available in SDKv11. If I remember correctly, BLE 5 was introduced after SDK11. This means that you have the option for 2Mbps on the nRF52. In short terms, this means that you can send packs quicker, and you can turn off the radio quicker, so it will use a bit less power.
The peripherals and everything else is pretty much the same, as it is hardware dependent.
