The GOTY package includes some extra loot boxes and skins, plus bonus Overwatch-themed content for Blizzard’s other games as well.
[Overwatch] Bonus Loot Boxes: Enjoy 10 Standard Loot Boxes, each containing a collection of random items that can be used to customize your favorite heroes. Loot Boxes may include skins, emotes, victory poses, voice lines, sprays, portraits, and highlight intros, as well as credits you can use to unlock a variety of different customization options.
[Overwatch] Origins Skins: Pay homage to the original Overwatch strike force with vintage skins of Blackwatch Reyes for Reaper and Strike-Commander Morrison for Soldier: 76. Explore other heroes’ origins with Overgrown Bastion, Security Chief Pharah, and Slipstream Tracer.
[Diablo III] Mercy’s Wings: Slay demonic forces throughout the High Heavens and Burning Hells while donning Mercy’s wings, and all of Sanctuary will know of your allegiance to Overwatch!
[StarCraft II] Player Portraits: These picture-perfect portraits of Tracer, Reaper, Pharah, Winston, Bastion, and Soldier: 76 give new meaning to the phrase “Hero of the Koprulu Sector.”
[Hearthstone] Overwatch Card Back: If you happen to find yourself in a Tavern Brawl, show your opponent you’ve got backup with an Overwatch-themed card back.
[World of Warcraft] Baby Winston Pet: Adorably cuddly and highly intellectual, the Baby Winston pet will be at your side as you fight to extinguish the Burning Legion.
[Heroes of the Storm] Tracer Hero: The cavalry’s here! Jump into the Nexus with Tracer and surprise your enemies in the blink of an eye.
Amazon shows these as currently out of stock, but after Googling around a bit, that seems to be an error (or a way for Amazon to get around their typical 20% Prime preorder discount), because this should come out on July 28.