That was how these LED TV got started but manufacturers have now made a variation to this to cut down the cost. Instead of having the LED lighting at the back (normally called full array LED), they place the LED along the sides of the LCD panel for the lighting and this is termed LED edge-lit LCD TV but again the marketing guys are not too keen to tell the difference and this is also simply called LED TV. Consumers are also not bothered as long as the HDTV screens look good.
In theory, the full array LED can perform better than edge-lit LED (and more expensive) since each pixel on the LCD screen can be control individually by the LED array while the backlighting by edge-lit LED is not so precise. Thus the outer edge of the screen may appear brighter. However, with improving technology, the difference may not be so obvious.
The main advantage of these LED TV over the normal LCD TV is that they are thinner and consume less power. Manufacturers also claim that LED TV produce better image with better contrast, blacker black and faster respond time compared to LCD TV, even approaching that of the Plasma. How much better varies from model to model but generally the higher the price, the better. On the other hand , some viewers find the LED TV to be too sharp and too bright and thus unreal and unnatural; a little too perfect since after all we live in an imperfect world!
The main disadvantage of LED TV at the moment is of course, the price, as it is the most expensive among the three flat-screen TV of Plasma, LCD and LED. But price will surely drop as more LED models become available. However, they still cannot compete with Plasma in the viewing angle.
Knowing the differences may help in your decision but finally whether you prefer a Plasma, LCD or LED TV is in the end a personal choice and so let you eyes be the judge. There are other features that you may want to consider, but these may or may not be critical depending again on personal preference.
Maybe I should just mention here that the latest marketing hype in HDTV is the 3D TV. Since this is priced beyond the reach of the masses and currently has not many source material to play with, we will not discuss them here.
My next post will be on deciding screen size. So stay tuned.