Easiest way to I.d it as a Pro for sure is to power it up.
Rb25det PRO example
The hand controller will say:
'EJ207 Pro
Power FC
version x.xx'
Otherwise open the case and look at the CPU.
Heres an rb25det pro chip, all PRO models are marked like this...your should say 'ej207 pro' if its a legit one.
Here's a link to everything power Fc:
clicky!