The RTK solution is filtering out data real time, the ppk (pps really as matt pointed out) is taking all the data collected and filtering after the fact using differing algorithms. In both cases the solution is depending on the static/rapid static (for lack of better terms) position of the local base (BCP). But you can have a third solution that will give you a position independent of the local base. In DPOS settings (the gear looking icon) you can select to also show a cors post processed solution. You might want to do that if you have cors stations that are close, or if you are doing a relatively short base occupation on an unknown coordinate. When you look at the points you will know because you will not see BCP; I can't remember what you see instead (PPK-COR maybe?). I have tried this just to see how things look, and get a few centimeters difference; but that's why I don't use it much because the nearest cors is usually 25 miles away so the local base is better reference (as long as occupation time and base location are reasonable).
Everything goes well.
I would send it to OPUS again now, just for curiosity sake. I've found DPOS to be better as well, but usually there's not a situation where one is really terrible and the other really great. I've read that sometimes a particular CORS will have a problem for a time and you can remove it from the solution until they get it fixed. I wonder if this is what happened on your first OPUS submission. Or look at your original OPUS solution and see if there is one station that is way out and affecting the results. OPUS rapid static will use up to 9 and might have included one too far away that screwed things up as well.
I think not enough time for the conditions. Sometimes 15 minutes will yeild a good solution in thick stuff but not always. You may need as much as thirty minutes or even an hour. And there's no way to know your right with just one static solution even if it returns a fix.
