A:Answer Both series include a built in Roku operating system, 4K UHD, and HDR Support. The 5-Series builds on this and has additional features such as Dolby Vision, wide color gamut, HDR Dynamic Contrast, etc. You can also visit www.tcl.com/products/home-theater/5-series and scroll down to "Compare All Models" to see all models compared. Hope this helps! Thank you, TCL Customer Support