While both LCD and LED televisions are lighter and thinner than the cathode ray tube technology they replaced, there are some key differences in how they each create high-definition output.
As its name implies, liquid crystal display (LCD) televisions rely on a combination of liquid crystals and cold cathode florescent lamps (CCFLs). The white light illuminates crystals and an imact is created as it passes through. LCD TVs use less energy and offers a wider viewing angle of up to 175 degrees compared to old-style CRTs. Also, there is less risk that an image will "burn" into the screen compared to plasma televisions. The downsides include a low contrast ratio and a lack of true black picture quality.
While LED relies on a similar process to create a high-definition image, the technology uses light emitting diodes (LEDs) instead of CCFLs. This corrects the black spots that can plague LCDs. They also offer an improvement in terms of energy consumption, color levels and contrast ratios. LED TVs can provide more accurate color than LCD TVs because they use red, green and blue lights (also known as RGB).
Both of these technologies are edging out plasma TVs in the consumer market; although plasma can be a bit bulkier, they still offer the widest viewing angles and are closest to theater-quality pictures of all of HDTV display technologies.