TCL 85S451-CA and TCL 85Q9BK offer different motion rates (60 Hz vs 144 Hz), which can impact smoothness during fast-moving scenes like sports and gaming. TCL 85S451-CA and TCL 85Q9BK differ in resolution (UHD vs 4K 3840 x 2160), which can affect overall clarity and sharpness of the display. Both TVs provide standard built-in audio performance suitable for regular usage, though external speakers can enhance the experience. Both TVs come with smart platforms that support popular streaming apps and voice control features. Both TVs offer adequate brightness levels suitable for most indoor lighting conditions. Overall, both models are capable choices in their segment, offering a balance between performance, features, and usability. If you're comparing TCL 85S451-CA and TCL 85Q9BK, both models come with modern features and are designed to deliver a solid viewing experience across different use cases. Both TVs come in similar screen sizes, making them suitable for comparable viewing setups and room environments.

Verdict: Choosing between TCL 85S451-CA and TCL 85Q9BK depends on your usage, whether you prioritize display quality, smoother motion, or smart features.