http://bugs.winehq.org/show_bug.cgi?id=24928
--- Comment #19 from Danellos trevor.w.philip@gmail.com 2010-11-07 04:04:09 CST --- Ah ok, I understand what you mean.
The main difference is the reflections on the water I believe, and other subtle special effects. I think the main purpose of the dx11 API was to provide a means for better gfx memory management for Win7/Vista users.
Although Blizzard is still using OpenGL 2.1 on their Mac client, I believe the Mac OpenGL is slightly different from ours. Thus their OpenGL would have a higher shader model support. Just thought I'd say this for interest's sake.