It's an HP-2 with a software/screen mod (one would think so since it is a newer model) in a different case...smaller screen and vertical design...not that hard to figure out...oh ya and an additional ~300$ added to the price tag.
The SDS series was the first Software Defined Radio (SDR) scanners released, period. Uniden's own well documented literature spells this out very clearly. The HP-2 is based on the HP-1's design, adding TDMA capability for P25 Phase II decoding. The BCD436HP and BCD536HP are more closely related to the HP-1/2 than the SDS series are.really and what would make you say that? Considering the parts content of them both is nearly 99% identical..(not including the screen and case of course) and even the processors are of the same family albeit a newer version with a higher amount of memory and the SDS100 does have a co-processor - both operate on the home patrol menu embedded OS system, both are SDR's although the addition of the parallel IQ for co-processor is utilized in the SDS100.
SDS100-SS.pdf


SDS100 Prerelease Discussion
True. But if uniden trunks nxdn it will be the nxdn leader. True , but I don't think you'll be seeing NXDN anytime in the near future. And Whistler still has to play their hand sometime soon. It will be quite interesting in the next few months.