Definition of LCD and OLED
Simply put, an LCD screen is a liquid crystal display that cannot emit light on its own and requires backlight support. The backlight emits white light that passes through a color filter to project the three primary colors. Abandoning complex principles, Hao Ge will give you an analogy. LCD is similar to a neon light shell, which cannot emit light on its own. It displays neon colors by penetrating the colored outer shell through the internal light.
OLED is an organic self luminous material that possesses luminescent properties. When an electric current passes through it, these organic materials will self emit light, projecting the three primary colors of red, green, and blue. It's like an advertising board filled with small light bulbs, each bulb can emit three primary colors on its own.
So, the main difference between the two is that LCD cannot emit light on its own, while OLED can emit light on its own.