What is the MAIN difference between OLED displays and LED displays?

The main difference between OLED (Organic Light Emitting Diode) displays and LED (Light Emitting Diode) displays is that OLED displays use self-emitting light sources. In OLED technology, each pixel emits its own light, allowing for better contrast ratios and deeper blacks, as pixels can be turned off completely. In contrast, LED displays use a backlight to illuminate the screen, which can result in less precise control over brightness and contrast.