There is a huge difference:
One of them happened off-screen before WoW even existed, just written lore.
The other one was made to be experienced by the player on both sides. As a night elf fan I'm telling you, experiencing The Burning of Teldrassil scenario was not enjoyable, it was not fun. It was a dreadful. And I regret ever doing it.
And yes, I think there should be repercussions for the Horde. Live. Sylvanas should be executed publicly, with a juicy cinematic indulging in the same kind of cruelty and torture they rubbed into Alliance players faces with Varian and Delaryn. The Horde should be made to rebuild what they have destroyed and to vacate Ashenvale, Darkshore and Feralas completely and unconditionally.