Reskins, reskins and more reskins. Same shit given a new cover and sold to us as new. That's what 10m+ subs get you.
And Kil'jaeden at the Sunwell was really him. You could argue that he hadn't come completely through the portal, but I don't see how that would affect his power. Maybe he was sucked back through before he could bring his full strength to bear. I'd still put him below Old God level.
If you like my draw-rings. http://yig.deviantart.com/
If you can't find them for some reason beyond that page. http://yig.deviantart.com/gallery/
WOW screenshot and concept art gallery http://smg.photobucket.com/user/evilknick/library/WoW