Difference Between Ceramic And Composite Back Apple Watch

Yes the composite is plastic.
Difference between ceramic and composite back apple watch. Difference between composite and ceramic back. More durable or more scratch resistant which one. For apple watch sport the series 0 and 1 both have composite backs while the series 2 has a ceramic back. The titanium apple watch on the other hand has two colors and starts at 500 less than the ceramic model.
So the series 2 watch now has a ceramic back in all models whereas the series 1 does not. What s difference between composite back and ceramic back. Does the ceramic vs composite back make any difference in terms of scratching hardness etc. It s greater price gap in fact than the one between the starting prices of the aluminum and stainless steel watches.
Thank you for your answer.