LCD stands for Liquid Crystal Display which is a thin, flat display screen made up of any number of color or monochrome pixels arrayed in front of a light source or reflector. Note that LCD required an external light source and its liquid crystal materials emit no light of their own, rather they block it. They produce a display by selectively blocking red, green or blue light.

LED stands for Light Emitting Diode which is a semiconductor diode that emits light when an electric current is applied. This effect is a form of electroluminescence. LED has many diverse applications but mainly fall into these categories:

1) Visual signal application i.e. LED displays used as television displays, electronic billboards, dynamic decorative displays, advertising display panel
2) Luminaries i.e. light bulbs, architectural lighting, backlighting for LCD displays
3) Non visual applications i.e. remote controls, movement sensors