There are many types of inline skate wheels for the different inline skate disciplines, styles and skating conditions.
One thing that makes them different is the wheel profile, which is the shape of each wheel from a head on view. The profile establishes how much of your wheel touches the ground when you skate. There can be a big difference in the profile views of wheels, and each profile has a purpose. Wheel profiles and sizes are different depending on the skating discipline. Inline hockey wheels, recreational wheels and figure or dance wheels can work across these same disciplines, but you should be aware that you will not have all of the wheel properties needed for the activity. Recreational wheels are usually multi-purpose, but again, you will not have any sport-specific wheel benefits. The profile (shape) is also important; a wider flatter wheel has more traction and grip, but also more rolling resistance and won’t glide as well. Aggressive skaters prefer smaller flatter wheels for their grip and control, while speed skaters prefer taller narrower wheels because they offer less rolling resistance more responsiveness.
Another thing that separates wheel types is the wheel durometer or hardness of the wheel. The higher the durometer number, the harder the wheel, and the harder the wheel, the longer it will last – but a hard wheel gives a rough ride and provides less grip on your skating surface. The smaller the durometer number, the softer the wheel, and the soft wheels grip much better and ride smoother but don't last as long.