Is 4K resolution and an optical drive worth an extra $200 to you? That's the main difference between the $499 Xbox Series Xand $299 Xbox Series S. The Xbox Series X has more memory and better processing components that run at faster speeds than the Series S, but it's all in service of hitting 4K and 120 frames per second while gaming without upscaling. For streaming video, the Series X can do native 4K and upscale to 8K, while the series S upscales to 4K.