The 2015 is Windows Certified whereas the BETA isn't. But the BETA is a newer driver than the 2015.
If 16.3.1 is not listed it normally indicates it may not be compatible. You can always install it and see if it works or not. But you may need to go into Safe Mode to remove it.
You always install the APU driver which automatically installs the Discrete GPU driver for your laptop. Seems like your APU is considered to be legacy and not supported by AMD with any new drivers.
By the way, AMD stopped supporting Windows 8.0/8.1. There are no new drivers no matter how new your GPU card is.