DTV (digital television) and HDTV (high-definition television) are referring to the type of broadcast; SDTV (standard definition television) is referring to the type of TV. DTV means that the broadcast is being sent out digitally. HDTV is a form of DTV and is the highest quality of broadcast today. SDTV allows you to receive and display a digital picture, but not HD.
There are many quality levels of digital television programming. The most common are:
Standard definition TV (SDTV) – SDTV is the basic level of quality display and resolution for both analog anddigital. Transmission of SDTV may be in either the traditional (4:3) or widescreen (16:9) format.
Enhanced Definition TV (EDTV) – EDTV is a step up from Analog Television. EDTV comes in 480p widescreen (16:9) or traditional (4:3) format and provides better picture quality than SDTV, but not as high as HDTV.
High Definition TV (HDTV) – HDTV in widescreen format (16:9) provides the highest resolution and picture quality of all digital broadcast formats. Combined with digitally enhanced sound technology, HDTV sets new standards for sound and picture quality in television.