Generally, the difference between Standard Definition TV (or SDTV) and High Definition TV (or HDTV) is that the signal on the SDTV is more compressed than that of a HDTV. As the digital signal is compressed, basically, the broadcasters can transmit five SDTV programs, whereas HDTV can only broadcast one. Multiple program broadcasting, called multicasting, was not previously available with analog transmissions. The picture definition of SDTV is also slightly lower than on HDTV.
In addition to that, SDTV will give a greater range of choice in the type of viewing material you will be able to access. Children’s programs, documentaries, films, and public affairs — the choice will be far greater than before compare to other cable TV technologies, and of course, to your old – fashioned videocassette recorder technology. It will be just the equivalent of the different digital satellite services such as the Dish Network or Direct TV.