Cajun
Yes, there is a difference between the two!
The Classic, which is 12.75mm at the tip, will squirt the cue ball a little more than the Classic Pro, which is 11.75mm at the tip.
Remember, squirt (cue ball deflection) is the result of tip end mass. Meaning that the more effective tip end mass, the more squirt for a given shot. Being larger, the Classic will have more tip end mass than the Classic Pro.
I hope that helps!