Image Processor: The S90D comes with a newer processor (NQ4 AI Gen2), offering better resolution through AI and improved upscaling compared to the Neural Quantum 4K processor of the S90C.
HDR Brightness: The S90D has noticeably higher maximum brightness, enhancing the viewing experience in bright environments and boosting contrast in HDR content.
Motion Handling: The S90D offers better management of fast scenes, thanks to improved motion handling and technologies like Motion Xcelerator 144Hz (compared to 120Hz of the S90C).
Gaming Capabilities: Both support 4K at 120Hz, but the S90D supports up to 144Hz via HDMI 2.1 in PC gaming, making it ideal for more demanding gamers.
Operating System & Smart Hub: The S90D features a slightly updated user interface with improvements in speed and navigation.
Design & Materials: Design-wise, they remain similar, but the S90D has an even thinner bezel and a more premium finish.