High-definition televisions have upended the television marketplace. Before roughly 2002, if you bought a television, you had a television and that was largely that – there was no "regular upgrade cycle." Now, there are competing types of flat screen televisions, promises for higher resolution down the road and a lot of consumer confusion. There are two broad families to compare -- LED-backlit LCD displays, which are sometimes called LED displays, and plasma display technology, with newer technology on the horizon.
Old Reliable – Plasma TVs
The earliest flat screen and high definition television sets were plasma TVs, and plasma TVs have a diminishing place in the market, as LED backlit LCD displays have managed to beat them on price, and features, over the years. There are two places where plasma TVs shine. The first is large displays – anything over roughly 46 inches in diagonal measurement is going to be a plasma display. The second is contrast ratios. When a pixel on a plasma display turns off, it goes completely dark. LED backlit displays always have some light coming through the display. On the down side, for smaller TVs, plasma displays may have a lower native resolution, though most consumers won't actually see the difference at normal viewing distances.
It used to be received wisdom in the consumer television arena that LCD TVs were fine budget displays, but that for true high performance, plasma was the only way to go. This has fallen out of vogue as of roughly 2008, when the response times on LCD TVs got fast enough to eliminate the problem. Now the knock on LCD TVs is color quality and contrast ratios. LED backlighting helps in a slight way with color richness as each pixel can be brightened or dimmed individually, and significantly with saturation and contrast, for the same reasons. Plasma displays have a small edge here in picture quality, but the gap is narrowing.
The viewing angle on a TV is a description of how far away from dead center the viewer can be and still see an undistorted picture, or a picture where the colors don't wash out, tonally. One reason why plasma TVs are the go-to technology for larger displays is their wide viewing angles. The LED backlights on modern LCD displays don't improve the viewing angle concerns that much.
The difference in power consumption between a flat screen TV and older tube TVs is significant. Old televisions consumed a lot of power for routine operations. Even 50-inch plasma TVs consume less power than 20-inch tube TVs. LED backlit LCD screens are more effective still.
Future -- AMOLED TVs
Pure LED TV's don't exist – yet. There are engineering prototypes of Active Matrix Organic Light Emitting Diode displays. At the time of this article's publication, AMOLED displays are used on cellular phones and a few tablet devices; they will eventually migrate to laptop screens and large format televisions. AMOLED promises to marry the rich blacks of plasma TVs with the power sipping nature of LCD flat screens, while having richer colors than either. For now, though, unless you need a very large television, or are building a high end home theater, LED-backlit LCD TVs are the way to go.