You stated that the 6.5 Creedmoor is the ballistic twin of the 260 Rem (see post #58: It has exactly the same bullet performance, bullet weight, selection, style, velocity, same magazine size, bolt face, etc. EVERYTHING. How is one "better" than the other?) and I agree.
However, the Creed does this with less powder and in a smaller package that is easier to fit in SA magazine. The lower powder charge and more efficient case design will lead to a slightly longer barrel life. Some would also argue that the lower powder charge could lead to less recoil but I am not 100% sure I buy that but the thought is out there. The long neck and OAL of the creed will also allow you to chase the lands for a longer period of time while still being able to effectively mag feed. Better accuracy could also be inferred as the long neck could help probably align the bullet with the bore but again that is probably more of an academic argument than one that would show up on paper.
You now have one tiny reason as to why the Creed is better - slightly better barrel life.