Dchan, I hope this isn't in response to my post in your last video thread...
In my mind, theres absolutely nothing wrong with park and ride turns. I love doing them, and due to laziness, its probably 95% of what I do when I'm on groomed snow. They're fun, effortless, and you get some great sensations. My point was, its really hard to take a park and ride turn and shrink it down into a short radius turn.
To me, the main difference between park and ride turns and my shorter "all-mountain" turns is the amount of setup and inner leg manipulation. For shorter turns, I have to unweight my upcoming inside ski, guide/manipulate it a little bit, and aggressively tip it toward its little toe edge. These turns are pretty carved, but there can be smearing through the second half of the turn.
In a PnR turn, you can balance your weight on both skis and just roll them from edge to edge to make nice big sweeping turns. The amount of carving is very high, you produce very rail like turns. Size depends on the sidecut radius of the skis and the amount of angulation you can add.
With short slalom skis, you can make some pretty tight radius turns with the same level of carving. These are what slalom and GS racers do. I don't like calling them park and ride because they're actively moving their c.o.m. inside throughout the turn and using guiding movements. These are what psia instructors are all obsessed with now.
For my skiing, I don't feel like these tight slalom turns are appropriate for steep, bumpy, or challenging terrain. You really have to be on your game in order to keep your speed "in check" since all the speed control depends on turn radius. For some reason though, instructors (a lot of them on this site) seem to be pushing this for the majority of the skiing public. I think its way beyond what most recreational skiers will ever hope to do.