If there is any takeaway from the presentation, it should be that while both Optical and Passthrough MR headsets are worn on the head, the type of applications they support are mostly very different. Optical MR emphasizes seeing the real world and adding to it. Passthrough MR is augmenting the virtual environment.
Source: Slides From Presentation at AWE 2023 on Optical versus Passthrough MR – KGOnTech