Hi
@pem2ati
Although Hikvision refers to these ranges as Pro & Ultra, there actually isn't a huge amount of difference between these models.
When the 3-series Ultra range was first announced it took a lot of digging and emails with Hikvision support to get a clear answer as to what the difference was between the 2-series & 3-series, below is a list of the things the 3-series models include that the 2-series do not:
5-year Warranty
4 Video Streams (rather than 3)
DC 12v Power Output (for connecting/powering alarm devices)
Low bandwidth solution (Smooth streaming, EPTZ)
Safety (SRTP, SFTP, SD card encryption)
Audio abnormal detection
5MP Resolution (instead of 6MP)
The majority of these small changes are things that would only be important to professional, high-security installations and add to that a higher price tag, less stock being available, and the fact they basically run the same firmware/software as the 2-series, we have decided not to sell this range at this time.