You can tell that there is a difference between the two based on what they refer to. HDTV means high definition television while the plasma is considered to be a new type of television technology. There was a time when the television seems to be very uncomplicated because people can have a similar type of television wherein the only differences are the colors and the screen size.
Right now, there are different television types and people will always aim to get a high definition television so that they can watch their favorite shows and movies with ease. Aside from the plasma television, other television types are LCD, LED, and CRT. Most of the plasma television types that are being sold right now are HDTV.