Its better to say new races the new species. Imagine someone reading on a box "NEW SPEICES!" rrriigghtt
Yes they are different species and that's a good reason to keep fighting indefinetely. There can never be peace in azeroth until it's dominated by a single species.
I'm sure the idea of the shattered landmass's floating in the twisting nether (a bump in logic and physics in it's own right) while still allowing creatures to breathe and gravity to remain, especially considering how small Outland is.
By that same exceptions of science die to fantasy world, race and species do not mean the same thing in the Warcraft universe as they do in the real world. This is an even simpler exception since the language (Common) that Humans use in the universe could have evolved much differently from English; hell it may be a different language entirely. For instance names like Tirion, Bolvar, Varian, Anduin are not existent in English (though someone may have used them you get the point).
Due to the evolution of language and the flat out fantasy world exception there are indeed races in WoW.
“4chan once took on the FBI and won,” a Brony told the New York Observer, “so you might say that My Little Pony is more powerful than the FBI.” Sethisto
this is a linguistic issue
not a biological issue.
we are talking about how words are used and defined in context, not how organisms are systemized into clades.