The much higher resolution in a HDTV produces clarity and vibrant colour, which was not seen from a traditional TV. The usual analog TV screen has 525 scan lines for each image, with 480 actually visible. The traditional TV has an effective picture resolution of about 210,000 pixels. In the highest resolution digital TV formats, each picture contains about 2 million pixels, which means about 10 times more picture detail on the HDTV screen. With digital television, the transmission of the signal is from the satellite dish directly to the satellite receiver that decodes the signal and broadcasts it to your TV set.
Another difference between the traditional TV and HDTV is the difference between a progressive and interlaced signal. The differences between the two can be characterized by the way the image is displayed on the screen. With interlaced format in case of HDTV, the information is filled in first with the odd lines on the screen and then the even lines. While the movement on the screen is so fast it's not easily detectable to a human eye, you may have experienced a 'flicker' quality with interlacing.