A few things I have noticed:
* The comfort setting on 08-15 is softer than the 16-21. The 16-21 feel, less "squishy" in comfort mode. I prefer the 08-15 for comfort mode.
* The sport setting on the 08-15 feels slightly more aggressive than the 16-21. The difference is small, you may not even notice. The 08-15 feels like it is trying to tighten up the suspension way too much for such a large vehicle. I prefer the 16-21 "sport" feel.
* When coming to a stop from higher speeds they both lower the rear (after the rear was raised at higher speeds). The 08-15 drops quicker and is more noticeable. The 16-21 lowers also but it's more gradual and not as noticeable. 16-21 wins here.
There might be other differences. Those are the ones I notice.