No. HDTV is the highest quality of DTV, but it is only one of many formats. In addition to HDTV, the most common formats are Standard Definition Television (SDTV) and Enhanced Definition Television (EDTV).
SDTV is the baseline display and resolution for both analog and digital. Transmission of SDTV may be in either the traditional (4:3) or wide-screen (16:9) format.
EDTV is a step up from Analog Television. EDTV comes in widescreen (16:9) or traditional (4:3) format and provides better picture quality than SDTV, but not as high as HDTV.