With traditional NVRs, Dahua's "IVS" (and Hikvision's "Smart Events") are brand specific, meaning the brand of the NVR needs to match the brand of the camera to utilize.
No technical reason for this, both companies offer an electronic interface on the cameras that lets anyone tap into those types of events. For example, the
Blue Iris (NVR software that runs a PC) can tell when a Hikvision "Smart Event" is happening and start recording. I'm sure the author could make it work for Dahua IVS if he had the proper information (and motivation).
That's not the case with Motion Detection. You can mismatch NVR/camera brands with that. But for most people, it's impossible to tune Motion Detection to be as good (in terms of not "false alarming" frequently) as IVS.