Stopstart i think you need to fly Airbus. They like to over complicate things. Boeing keeps it simple vref is vref v2 is v2
The only thing in common the 2 have is that they are both based on Vs.
In the absence of improved climb V2 = 1.2vs whereas vref is 1.3vs (for their reepective flap settings.)
1.2 x a higher speed (flap20 Vs ) is close to 1.3 x - a lower speed (f30 vs)