I've seen a lot of posts about the difference between polyurethane and urethane bushings and other parts.

I found this site that explains it in detail http://www.aragonelastomers.com/faq.htm#question3

Here's a summary of what they say:

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What is the difference between polyurethane and urethane?


As shown above, polyurethane is just "many urethanes", so, technically, urethane is just the chemical group shown above and polyurethane is a material than incorporates many urethane groups.


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What are the major reasons to use polyurethane?

Polyurethane can be formulated to possess superior properties in the following categories:

Toughness
Abrasion Resistance
Cut Resistance
Long term stability in outdoor environments (no cracking or hardening over time)
Soft materials that can stretch up to ten or more times their length.
Hard materials that are not brittle--even at temperatures of 40 below zero.
High or low friction formulations
High or low energy absorption formulations (i.e. bouncy or dead)
Custom formulations for many widely diverse applications
Economical prototyping in liquid poured systems to test formulations and design.

Hope this helps....

-Mike in Colorado