The difference between an LCD and a Plasma TV is that a Plasma TV uses charged neon and xenon gas to hit red, blue and green phosphorus to create an image on the screen; whereas a LCD TV uses two pieces of fused, transparent material that uses special glue that holds liquid crystals. A light source allows charged liquid crystals to accept or not accept light in order to create an image.
Here are the similarities: they both have flat screens, they both have sharper images than a CRT, but the Plasma TV has a shorter screen life and generates more heat than a LCD TV. If picture sharpness and brightness of color is important to you, the Plasma TV is a better bet. It is available in larger screen sizes more commonly than is the LCD TV. Another advantage of a Plasma TV is it can be cheaper to buy than an LCD. The main disadvantage of the LCD screen is that if the individual liquid crystals burn out, than there will be little black and white dots on your television screen that cannot be repaired without replacing the whole screen.
The main disadvantage of a Plasma screen is that a picture left on too long can burn a permanent image onto the screen. I also wonder about the safety of having all of those chemicals around: neon, xenon, red, blue and green phosphorus, but sources I have found indicate that Plasma TV’s only generate a small amount of ultra violet radiation, and less than the traditional CRT TV’s