What's the difference between DTV and HDTV?

Digital TV is the way the picture is transmitted.  HDTV stands for high-definition TV.  HDTV is the type of signal we're sending when a show is produced in the HDTV (also called 'high-def') format.  Not all digital TV shows will be in high-definition.  But all digital TV looks and sounds much better than the current signal.