I have seen the very early belts from 2000 with vertical markings on the belts (and some years after than with markings like an arrow).
The new ones are made by Continental for Otis and have no markings on then, they are smooth in the surface. From my experirence the new belts are not as good as the old, higher slip rate and they tend to fail faster.

But the specs are the same, mayby just cost reducted ;-/

/Alex