Face Detection vs IVS

Hi all,

I am slowly learning and getting my NVR and cameras set up. My current step is trying to get notifications working. I can get things like Motion Detection, Cam Masking and Scene Changing working via the DMSS app, but have not had any luck with smart features like face detection, human/vehicle detections, tripwires etc.

I realise some of these may only be available whether I select Face Detection or IVS in the Smart Plan section, or maybe they are not available on the particular hardware I have (it was all already installed in the house I bought).

So my questions are:
  1. What detection/notification features are available with Face Detection vs IVS selected?
  2. Are my cameras/NVR combination even compatible to use these features (models below)? I looked online and it appeared the cameras have IVS, but not sure about the NVR. It looks like it has SMD, but when I go there in the NVR it says "The config is not supported".
NVR: Dahua DHI-NVR4104HS-P-4KS2
Cameras (connected to the NVR via PoE: DH-IPC-HDW4631EMP-0280B

Thanks in advance!