Specifically the promos and the name of one of the themes from the sets.
Flames of Destruction unleashes the full power of the elements with the new “Elementsaber” monsters, a new monster theme that works with the existing “Elemental Lord” monsters. To celebrate this release and give players a second chance to get the older (and sometimes hard to find) Elemental Lords, each Flames of Destruction Special Edition box comes with 1 of 2 Elemental Lord monsters, either Moulinglacia the Elemental Lord or Grandsoil the Elemental Lord. Moulinglacia, the Elemental Lord of Water, was first released in 2012’s Abyss Rising booster and has never been reprinted, until now. Grandsoil, the Elemental Lord of Earth, after first appearing in 2012’s Return of the Duelist, was toppled from his throne and is currently not legal for play, due to his incredibly high power level, but will be receiving revised card text and restored to tournament legal status with this release.
Each Flames of Destruction contains: 3 Flames of Destruction booster packs, either Moulinglacia the Elemental Lord or Grandsoil the Elemental Lord, and 1 of 2 Super Rare preview cards from the upcoming booster set, Cybernetic Horizon.