There's a bunch of differences. I think the plasma technology is older and it will probably be fazed out in some years from now, but it seems the plasma TVs have better image quality in a number of areas, for example it's supposedly 'quicker' (600Hz) and has better contrast -> better blackness, but they're also much thicker, takes more power and has some other issues as well.
Plasma seems to provide better image quality for it's price, but LED is stylier... My old CRT TV died a month ago, so does anyone have any good insights? A 42' Panasonic Plasma looks pretty attractive atm...
Are data monitors possible and a viable option if TV-watching and perhaps some gaming are the main uses?