What is the difference between the standard EVA seat cushion and the Locus Seat Nubuck upgrade?

All Locus Seats come with a comfortable EVA closed-cell foam seat cushion. With Locus, the standard seat has a choice of three colors: Black, Chili Pepper, and Citrus. If you want to upgrade to the Nubuck cushion, you will receive the EVA seat cushion upholstered in a synthetic black Nubuck. Nubuck is a very soft, sueded Japanese synthetic leather.