A:Answer I questioned several Best Buy clerks, and later did research on my own, and it seems the main (and maybe only) difference is that the m2 version has Dolby Vision. Since there is almost no content available that is filmed/produced in Dolby Vision, and since the m2 version is more expensive, I went with the older UBP-X800 version. My TV does have Dolby Vision, so if I ever do find any Dolby Vision content, I can still watch it.
