These three machines are almost exactly the same and are very programmable. The main difference is that the S9 comes equipped with both a two-position steam wand and an auto frothing system that is easily interchangeable. The S7 and S8 come with the two-position steam wand only. The other differences are the colors, the S9 is Bronze Metallic, S8 is Platinum and the S7 is Black. We have an article explaining more about the Jura Capresso S9, S8 & S7