Quote from Superhero Hype:
Though WB confirmed that an "Ultimate Edition" will be hitting later (around Christmas), Snyder emphasized that the July edition's features won't be repeated and that the later release will be a more or less "movie-only" version, incorporating the "Black Freighter" footage back into the film. Though the later set's running time will be the longest version possible, Snyder's preferred cut will be the version hitting July 21st and that that version will contain the greatest special features. While the "Ultimate" version will not include the walk-ons, it will have an exclusive audio-only commentary.
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Seems if you want the longer "Ultimate" cut + special features, you will be forced to get both releases...