There is a difference. Sylvanas lit up the tree after several hours of intense battle on Darkshore, allowing people to time to evacuate Teldrassil. The Alliance struck with absolutely no warning after diverting all military forces to Nazmir. The Zandalari had no chance to evacuate anyone. The Alliance just started fucking the place up before murdering the King.
Yes, this! The whole premise behind classic WoW was the trope inversion: the Horde was a noble, diverse, and inclusive group whose primary focus was honor and welcoming the downtrodden and homeless; while the Alliance was corrupt, racist trash literally controlled by the black dragonflight! It's pretty explicit in pre-Cata WoW that the Horde is the good guys and the Alliance is the bad guys, and that subversion of expectations is one of the things that made it so interesting.
Basically, I want Thrall back. I guess Baine or Saurfang would do in a pinch.
Tangentially related: it kinda looked to me like they're really setting up Talanji as the new leader of the Horde, but that seems like it would be a hard sell to the guys back in Kalimdor…