I feel like it used to be size, color, and clarity meant more expensive. Now I look at a 500$ 4k TV and a 2000$ 4k TV and I don’t know what the difference is. They can both be smart TVs, be the same size, and have a lot of same advertised features, but what are the subtle unspoken mysteries that justify a huge price gap?
How small the lights are in the back
Edge-lit is just one big light, no dimming zones.
Direct-lit are big squares of dimmable zones in the back
Mini-led are small squares of dimmable zones, like Direct-lit but smaller
Quantum-dot Led are even smaller squares of dimmable zones that are build-into the screen
And OLED is dimming at the pixel layer?
Quantum dot LED TVs don’t actually use quantum dot LEDs (yay, marketing). They’re built like any other LCD, but instead of having a white backlight (typically a blue LED with a phosphor to fluoresce the blue to green and red, too, making white) and then a colour filter behind each pixel subelement to only let the right colour through, they have a blue LED backlight, and then a quantum dot film that fluoresces the blue to the right colour.
The advantage of this is that you’re not making light in colours you can’t use just to get absorbed by the filter and turned into heat, so can make the backlight brighter, which, when combined with other techniques to make good LCDs, is enough to make them comparable to OLEDs in quality and price.
Actual quantum dot LEDs let you make light at practically any frequency you want, like OLEDs (traditional LEDs only make light at bandgap frequencies for atoms of elements, and there’s not a huge choice of suitable elements, hence blue LEDs taking decades to materialise after other colours were cheap). In theory, quantum dot LEDs won’t have burn-in problems, but they’re currently not practical to make a TV out of, giving marketing people plenty of time to weasel out of their fuckup with naming existing QLED TVs.