An organic light-emitting diode (OLED) is a light-emitting diode (LED) in which the emissive electroluminescent layer is a film of organic compound that emits light in response to an electric current. This layer of organic semiconductor is situated between two electrodes; typically, at least one of these electrodes is transparent. OLED is the only technology capable of absolute blacks and extremely bright whites on a per-pixel basis.
QLED, or quantum-dot light-emitting diode, technology creates a picture in a notably different fashion than OLED does.
QLED is a marketing term created by Samsung to describe a technology it's been refining over the past few years. LEDs are used to hit a layer of quantum dots that glow at specific wavelengths in red, green and blue, to create colors. That picture is then displayed on the LCD panel.