I got grippers and there sick for both...
I think the grippers are for if you ride mostly park, but they are also for street. The sliders are mostly for street. Sliders slip out of park (espically wood) so if u ride mostly park, get grippers, if u ride mostly street, get sliders.
Grippers have a softer, more grippier urethane, where as the sliders have a harder, more slippery, and more tear resistant urethane, which makes them last longer then the grippers, but they dont have the grip and the performance of the grippers.
So, if you ride street, get sliders, if you ride park, get grippers.