Thanks for asking! The Picture: The QN800D & QN900D both feature Quantum Matrix Technology Pro with Mini LEDs, providing you with a billion color shades, intense contrast, and hyper-focused brightness and dimming in all the right areas. When stepping up to the QN900D, you’ll gain 8K AI Upscaling Pro and Neo Quantum HDR 8K Pro (Neo Quantum HDR 8K+ on 65”) for brighter brights, darker darks, and extra clarity. The Processor: While the QN800D features 256 neural networks, the QN900D’s NQ8 AI Gen3 Processor steps up with 512 AI neural networks that help update each scene. The Design: Both models feature an attachable Slim One Connect solution that neatly tucks cords and cables out of sight. The QN800D features our Infinity One design with a super slim, sleek profile. With the QN900D, you’ll gain our Infinity Air Design which allows the image to reach all edges of your TV, giving you a more expansive view for all your movies, shows and content. The Sound: Object Tracking Sound+ will give you directional, realistic sound that projects from speakers built into all side of the QN800D. With Object Tracking Sound Pro, the QN900D allows you to track on-screen action with sound coming from all sides of the TV – including the center. Gaming: While the QN800D offers 4K@165Hz, the QN900D adds additional enhanced gaming capabilities by supporting up to 4K@240Hz for PCs on all sizes. Hope this helps!
~ Samsung Specialist