There are plenty of threads addressing the differences, as far as software (firmware) goes, they are all equal, and directv considers all models (HR20,HR21,HR22,HR23) equal as well. The only actual differences are in hardware and appearance. The HR20 is primarly silver with the exception of the HR20-700B which is black, and extremely rare and you most likely will not get that. The 20s also have an integrated OTA Tuner. Some like it, some love it, some hate it. I dont do OTA (or Over the Air) so i dont have an opinion. I also believe this model has a 320GB HDD but im not positive of that. This model as well as the HR21 and HR22 have narrowband tuners and will require BBCs or Broad Band Converters to be used as well. I wont bore you with what they technically do as its not important, just know they are needed and will be supplied if you receive any of those models. The HR21 is nearly identical to the HR20 with two major differences, all models are black in color, and the OTA Tuner was removed. If you plan on using OTA you can have directv send you an AM21 to allow the receiver to access your antenna. This may or may not cost you additional money. The HR21 definitely has a 320GB Hdd. The HR22 is the same as a HR21 except is has a bigger HDD, a 500GB. The HR23 is where the tailspin comes in. This model has some minor and major differences. The 23 is black in color, has a 500gb hdd, but has wide band tuners, so it does not need BBCs. This is a major improvement in hardware, as it can read the Ka band natively without it needing to be converted. This next part I wont speak for because I cant see much difference, but the literal processing chips inside the unit of the 23 are suposidely a major improvement from Broadcomm and are supposed to display a crisper HD picture. As i stated, as a D* Tech, I dont see a difference. But the 23 is supposedly the best. The record light on the front of the receiver is also red on a 23 where it is orange on all previous. If i were you i would hope for the HR23 just because it is newest and has the latest hardware, but if you do OTA I would pray for the HR20-700B (dont count on that though, i would actually probably bet against it to be honest) The model you receive depends specifically on what the tech has instock on his truck. Some of us only carry what we need for the day, some of us have multiples of all receivers. That depends on what our HSP gives us, we have no control over what receivers we carry. Hope all this helps, post back with any questions.
