The basic terminology that is used to describe this technology space was defined by academic researchers over 20 years ago.  Unfortunately there is no universally agreed precise definition of basic terms like augmented reality (AR), mixed reality (MR) and virtual reality (VR).   Many persons working in this overall technology area now refer to the collection of these as XR.  The key to understanding this space is to recognize it as a continuum that ranges on one side from completely synthetic and immersive environments to the other side which injects digital artifacts into the real world in a manner that can be indistinguishable from physical reality.