A comparison of the two devices show that the cy5677 is confirm to the latest BLE 4.2 standard whilst the cy5670 is not.
Depending on the capabilities of the device you want to connect to you may use the (older) cy5670 which seems to be on stock.
Thanks for the reply, a small query,
1. does it have BLE 4.1 stack.
2. and does it support 250 MTU change.
Waiting for reply,