Probably several reasons both hardware and software. 1. LCD panel grade - panels are graded when they’re manufactured and Apple buys the ‘A’ quality panels whi

Probably several reasons both hardware and software. 1. LCD panel grade - panels are graded when they’re manufactured and Apple buys the ‘A’ quality panels while others including manufacturers tend to use a mix of different graded panels or buy the cheaper ‘B’ and ‘C’ grade panels which have uniformity issues and other perceptible defects. Back in the day Dell ultrasharps were famous for the ‘panel lottery’ where you weren’t sure what quality you’d get. 2. Other aspects of panels - There’s a lot of little things that go into making them that can affect quality including polarizers, backlight guides, anti glare, how they’re bonded, etc. Apple does a lot of investment in display tech (they did the first bonded lcds afaik which meant the pixels seemed like they were on top of the glass vs behind) and they doesn't skimp on quality parts. 3. Text rendering - At the software layer I believe Apple renders text a bit differently than Windows, and as of a few years ago killed text antialiasing, tho I’m not up to date on whether that results in qualitative difference vs Windows. 4. Target PPI - All Apple devices are made at target ppis - Mac around 227, iPad 264, iPhone 326 (lcd) - 480 (oled) - all of which correspond to a near equivalent size to our eyes when factoring in target distance from eyes for different form factors (e.g. phones closer, tablet middle, computer farther). Windows & Android devices are all over the place on this, offering tons of different scale factors that may affect. 5. Color correction - supporting ~100% P3 gamut colors on all modern displays along with the software to support it 6. Whole stack software optimization - when you control hw & sw, you can eke out a bit more qualitative improvement. For instance, knowing the panels are of a certain PPI and quality of color repro means you can pick UI colors (various greys etc) with much higher confidence, can create your own custom fonts that look great on them, etc, versus a sort of 'web safe colors' lowest common denominator equivalent you're stuck with on platforms like Win/Android with a lot of variance in device quality. Basically: you get the best visuals when you control the whole stack and invest in premium everything.