Rollers are small, but they decide how loud and smooth a garage door feels. A cheap wheel rides on the stem. A better nylon roller uses sealed ball bearings, commonly 6200ZZ-style bearings, so the wheel rolls instead of dragging, rattling, or grinding.
No real bearing. Usually cheapest and quiet at first, but wears, wobbles, and can drag in the track.
Durable but loud. As it loosens, it can rattle hard in the track and add shake to the door.
Quieter nylon tire plus sealed ball bearing support. Usually the best homeowner upgrade for noise and smooth travel.
The point of the 6200ZZ-style upgrade is not just softer material. It is the bearing. The wheel is supported by balls inside a sealed race, so the door rolls more cleanly under load.