So iTunes Store has the movie "The Dark Tower" in 4K Dolby Vision to buy for $19.99. I see the same movie at Vudu for $9.99 in what it calls HDX (what is that?). I purchase with Vudu because it costs less but I'm thinking it won't be as beautiful as Dolby Vision. After I purchased from Vudu, I went to iTunes Movie app on ATV 4k and the move was there under Purchased! Oh it's there in Dolby Vision! I'm guessing this occurred because I both iTunes and Vudu are within my Movies Anywhere account?