What is the difference between OLED and LCD displays?
The fundamental difference is where the light comes from. An LCD has a backlight shining through a liquid crystal layer that blocks light to form the image. An OLED has no backlight at all; each pixel emits its own light and switches off completely for black.
That single difference explains nearly every practical distinction. Because OLED pixels turn off, black is genuinely black rather than dark grey, contrast is effectively unlimited, and dark scenes have no glow or halo around bright objects. LCDs mitigate this with local dimming zones, and good implementations get close, but the zones are far larger than individual pixels so some blooming remains.
OLED also responds faster, which matters for motion clarity, and can be made thinner and flexible, which is why folding devices use it.
The trade-offs are real. OLED brightness in large full-screen bright scenes is generally lower than a high-end LCD can manage, which matters in a very bright room. Burn-in, where static elements leave a permanent faint impression, has improved substantially but remains a consideration for displays showing fixed interface elements for thousands of hours. Manufacturers include pixel-shifting and refresh routines to mitigate it.
Cost favours LCD, particularly at larger sizes, and the gap narrows each year rather than disappearing.
The practical guidance is that OLED suits dim rooms, film watching and anything where contrast matters most, while a good LCD suits bright rooms, all-day static content such as productivity work, and tighter budgets. For phones the question is largely settled, since almost all mid-range and above devices now use OLED.