Is there such thing as “different” XT/LT/PRO firmware or firmware is the same and it is some internal info (serial, flags, etc.) that define feature selection?

Hello! I have had Aquaero 6 PRO for some time and now in the process of rebuilding my PC with custom computer case. In the previous computer case Aquaero 6 was held in 5.25" bay but current case doesn't have any. And it's ok - I'll just cut out the window for it, no problem. But I thought that, if I'm creating new face plate for Aquaero 6 anyway - why not add additional 4 function buttons like in XT version? As far as I understand, Aquaero 6 LCD module has 8-pin header that is used to connect 7 ...