Difference between 2018 P-220 legion 10mm and 2021 p-220 legion 10mm

They are probably the same. Is the color the same too?

i believe one is cerakoted a more wet color and the other a lighter hard to explain

There should be no differences. Should not be even a color difference, but as anyone who has done much painting knows, colors don't always match.

On a side note, the P220 10mm Legion (only the Legion) is the only one that comes in BOTH SAO and DA/SA, with BOTH having fixed combat night sights. All other SAO P220 10mm came with adjustable target sights and no other variant of the P220 10mm was offered in BOTH SAO and DA/SA.

Why are you expecting a difference?

They should both be the same

If you are saying you see a difference in color, it would be because the earlier model is the original PVD finish versus the later cerekote finish. I own both and like both. The PVD Legion may have a flatter finish and maybe a bit more of a gray look.

Isn’t the barrel longer on the p220 10mm legion .

The P220 10mm has only been Cerakote as far as I know.