You will be shocked, but there are actually differences between 4.0 and 2.0. I have just checked out of curiosity. I wonder if it has something to do with the future shock. But, for instance, the reach on 2.0 in size XS is 388. It is 371 on 4.0. The TT on 2.0 is 552, it is 549 on 4.0.
The interesting one is the stack. And that would explain why many people recommend sizing down on 4.0. On the XS the stack on 4,0 is 590! It is only 555 on 2.0.

I am actually shocked that they seem to have 3 different geometries, depending on the model. I think this info is very important. One has to check the geometry of each model very carefully.