When I heard the word "mixed reality" for the first time two years ago, the idea was that AR was a 2d layer on top of reality (like google glasses) and that MR

When I heard the word "mixed reality" for the first time two years ago, the idea was that AR was a 2d layer on top of reality (like google glasses) and that MR was actual 3d objects merged in the reality. But then, mobile apps started doing the later and called it AR. Also, Hololens did what we were calling MR and called it AR as well. So at this point, I guess you can use whatever word you prefer.