There is a difference in screen size (39 Inch (99 cm) vs 40 Inch (102 cm)), and a larger screen generally provides a more immersive viewing experience. Both TVs provide standard built-in audio performance suitable for regular usage, though external speakers can enhance the experience. Both models support 1366 x 768 resolution, ensuring sharp picture quality with detailed visuals for movies, shows, and gaming. Intex LED-4001 and Sansui SMC40HB21C are two competitive smart TVs offering a mix of display performance, smart features, and overall value for different types of users. Both TVs come with smart platforms that support popular streaming apps and voice control features. Both TVs provide decent motion handling, making them suitable for everyday viewing including sports and action content. In general, both TVs cater to modern entertainment needs, including streaming, gaming, and everyday viewing. Both TVs offer adequate brightness levels suitable for most indoor lighting conditions.

Verdict: Choosing between Intex LED-4001 and Sansui SMC40HB21C depends on your usage, whether you prioritize display quality, smoother motion, or smart features.