They both have the same base. The difference is in the coating. All water based inkjet papers need a coating. The Somerset coating is made by St. Cuthberts Mill exclusively for Epson, where as the epson Velvet coating is made by Epson. The coating is somewhat similar to the Hahnemuhle coatings which "sit" more on the base surface and tend to "flake" a little with abusive handling, but these coatings do give a slightly higher D-Max, slightly higher resolutions, and higher color saturation. Try them both and descide for yourself.