LED (Light-Emitting Diode)

A semiconductor diode that emits light when charged with electricity. They come in diverse colors and some LEDs even contain multiple elements and are therefore capable of emitting light with different colors.

LEDs are used for displays, for keypad or display backlighting, etc. Bright white LEDs also can be used as flashlights and flashes for mobile phones. Even if they are not as bright as the xenon flash, LEDs are much more compact and require less energy - and also can be used as video light.

OLED (Organic Light-Emitting Diode)

A display technology that consists of small dots of organic polymer which emit light when charged with electricity.

OLED displays have several advantages over the LCDs. They are thinner, lighter, brighter, need less power, have better viewing angles, contrast and response time for video and animation. OLEDs are also cheaper and easier to manufacture.

On the other hand, LCDs offer better legibility in bright ambient light.

AMOLED display (Active-matrix organic light-emitting diode)

AMOLED is an emerging display technology used in portable devices like mobile phones. Active-matrix OLED displays provide the same performance as their passive-matrix OLED counterparts, but they consume significantly less power.

This advantage makes active-matrix OLEDs well suited for portable electronics where battery power consumption is critical.

LCD (Liquid Crystal Display)

A liquid crystal display is the most common display type among mobile phones because of its low power consumption and good image quality. They are generally easy to read, even under direct sunlight.

The smallest element of an image displayed on a LCD is the pixel. Each pixel normally consists of a layer of molecules aligned between two transparent electrodes, and two polarizing filters.

Some of the types of LCD displays are STN, TFT and TFD. The first one, STN, offers low cost and low power consumption, but low image quality. TFT features greater image quality and response time, yet its displays are more expensive and need more power.

Three other types of LCDs are transmissive, reflective, or transflective. Transmissive displays offer nicer image quality in low or medium ambient light, while reflective ones work best in bright ambient light. Transflective displays combine the best of both.

TFT (Thin Film Transistor)

TFT is one of the best Liquid Cristal Display technologies in terms of image quality and response time. However, it also consumes more power and is more expensive.

TFT, like TFD, is an active-matrix technology. This means a transistor is located next to each pixel, allowing it to be turned on and off individually. This ensures faster response time and greater contrast.

http://www.gsmarena.com/glossary.php3?term=led