Well, there are obvious differences which is to be expected when dealing with alternate universes.
I just look back at WoD and ask, what changed in the main timeline?
The only difference before and after is that Gul'dan enter the main timeline, and that Garrosh/Bronzie disappear.
So the expansion literary just served to be a reason for Gul'dan to be relevant.
Some lore fuckups aside, I geneuninely think he was the best villains Blizzard made in years.
But the reason I like it over pure alternate universe is that it does not alter canon lore, it adds on top of it.
That is the benefit of time travel, if executed well. *hint*