The Green Linen parallel set is only distinguishable from the Windsor Green parallel set by having a slightly textured border like woven linen. The Windsor parallel cards are smooth without texturing. I needed a magnifying glass to see the difference.

I read that the Serious Black and Black Linen parallels have the same features. Both of these are serial numbered to 99 making them more similar. So use the textured border to find the Linen versions.