A lot of our readers ask us about the comparison between the Roborock S50 and S55. But the truth is that there is no difference between the Roborock S50 and Roborock S55 except color. It's the same model called Roborock S5, some sellers use the number behind «S5» to represent the color of the robot. On Roborock's official website, the Roborock S5 model is presented in 3 colors, all models are available on Amazon (S55 is black, S50 is white, and S51 is white with rose gold details).Some sellers add a third number to the model name. For example, Roborock S501, which means the Roborock S5, Color White, FCC (US) version.You can check our review of the Roborock S6 which is one of the newer models released recently. There are also the Roborock S4, as well as the Roborock S5 Max in the model line which you can learn about by reading our Roborock comparison chart.Feel free to comment if you have any questions.