I'm not an engineer, so can't get into the technical differences, but, I have found that Delrin Top Hats and Spring Guides.
A, Reduce the mass weight, that has to move in a springer.
B, Reduces the Twang, as you do not have metal to metal contact.
There is something better i believe, it's like a self lubricating PTFE, Harvey Astell told me about it a while back.
Average Spring Gun Shooter