Also, if there’s a difference, what are they?
For your information, DTV and HDTV aren’t the same. That gives rise to a DTV vs HDTV discussion.
What’s the Difference Between DTV and HDTV?
In the DTV vs HDTV debate we’re talking about broadcasting standards, not physical TV sets.
DTV is the method whereby digital video signals are transmitted by TV stations and are received and processed by TV sets.
In this regard, DTV is the replacement of the old analog signals that have been used for decades.
With regards to DTV vs HDTV, it must be remembered that all HDTV broadcast can be called DTV broadcast but not all DTV broadcast can be called HDTV broadcast.
With regard to DTV broadcast, it also supports SDTV broadcast.
ATSC Digital TV Standards
ATSC (Advanced Standards Television Committee (ATSC) has laid down 18 types of TV resolution formats for digital TV broadcast.
All TV digital TV tuners, whether built-in or external are required to conform digital TV tuners are required to to these standards with the ability to decode the said formats.
Read More at about ATSC’s video standards at Wikipedia.