There are two types of abrasion resistance sliding and impingement. Sliding refers to scraping and rubbing abrasion while impingement refers to particles or objects striking the urethane surface at a high angle.
Polyether offers excellent impingement abrasion resistance which makes it the choice for sandblast curtains and bumpers that get hit head-on.
Both polyester and polyether urethanes perform well at elevated temperatures, however:
Polyethers is much less susceptible to dynamic heat build-up. That is why they are the choice for high-speed rollers where the rapid flexing creates heat.
All elastomers (rubbers, urethanes, silicones, etc.) get harder and less flexible as temperatures drop and will eventually reach a temperature at which they become brittle. Urethane's brittle point is between -40°F and -100°F depending on the formulation.
Polyether is less affected by cold temperatures.
Both polyesters and polyether can be made to any hardness from marshmallow-soft to bowling ball hard.
Products such as skate wheels need to return the energy they absorb when your foot pushes them into the pavement (rebound); otherwise, you would feel like you are running in soft sand. Sand absorbs most of the energy from your foot and makes you run sluggishly.
Polyether provides much higher rebound and therefore is the choice for skate wheels and high-speed rollers.
Sometimes you want the product to absorb the energy it receives (opposite of rebound).
Polyester is the choice for shock absorption and is used widely in vibration dampening applications.
Polyesters have higher tensile strength and higher cut and tear resistance than polyethers.
If the product is to be submerged or used in a very humid condition it should be a Polyether because polyether has excellent hydrolytic stability.
If the product will encounter oils, fuel or solvents (even vapors) your choice should be a Polyester as they are more resistant to attack from these harsh chemicals.