Somebody correct me if I'm wrong but the classic doesn't have a hollowed out core in the front end like the 314 does. So the classic would hit more solid in theory, and therefore might have a more crisp feel.
All OB's have a hollow front end of the shaft. With the OB1 and 2, the hollow extends all the way through the shaft to the joint. All but the last 5 or 6 inches is then filled with a silicone type rubbery core to dampen vibration. I believe the Classic and the Pro only have the hollow at the end and are otherwise solid the rest of the way through. This is how it *was* and I'm pretty sure of it.
Now that they transitioned to the + shafts, I don't know if any of this is still accurate. I would imagine it is.