What's the difference between these pistons?

[Unilevers]

(03-14-2016 )Mr Hagg Wrote:  Unilevers I was told at one time the compression ring was lowered on the newer pistons.

you may be right on newer pistons - but in this case it is not a matter of newer, just that one piston goes with the small cpls and one goes with the large ones. both those kits are the newest numbers for their respective cpl's and both are for anti polishing ring liners.