Picture this Tom. The abrasive particles of the 16000 are harder and more blocky shaped. The 8000 Jp are more like soft pancakes. So on softer carbon steels the scratches are flatter even though bigger and they don't have the bite of the harder abrasive.
When you get the time it would be good to see if my evaluation is sound or if it is way out in lala land. I trust that in time you will get the proper info from the technical people minus proprietary information. I know lots of this stuff is guarded and we are not asking for you to commit industrial crimes
Mike