Dark eldar Klaive.

[Dolnikan]

There however isn't much of any kind of source about the languages of the eldar, both dark and craftworld, being the same or different. It is one of those many areas where anything goes, as long as it can be fitted in. I think that the languages of the two subspecies will have remained roughly the same. The craftworld eldar are a conservative society where innovation is not a big thing. The dark eldar see themselves as the only true eldar, they use many things from before the fall and are proud of that.

Of course some changes will have slipped in but with the relatively large populations they have and their respective cultures they would mostly speak the same languages, there would be no more difference between the eldar from Commoragh and those of Ulthwe than between those of Ulthwe and Alaitoc.

[Draco Ferox]

I would say that the hatred of the Dark Eldar toward their "cousins" is what really differentiates them, and drives them to use weapons that are polar opposites; Eldar have mastered light, and make use of advanced laser weapons, wheras dark Eldar make use of darklight (think that's the term) and antimatter weapons. I do not, however, think that they would have differed much in terms of language. I was extrapolating the differences and similarities in langage from the tribal-esque look of the dark eldar runes, which would have been based off Eldar runes, but twisted and barbed by their fallen kin to resemble the hate that each feels inside. I am sure that a part of this drive to distance themselves is jealousy at the fact that no mattter what, they will inevitably have their sould taken by She Who Thirsts, but for the most part, I see them being more similar than any of their species would be willing to admit. I would say that innovation is a big thing on the craftworlds, but it is kept in check by the older Eldar, lest they slip back into the easy ways that lead to the fall. I all Eldar being able to communicate adequately, and some may even go so far as to learn the languages of other craftworlds, just as people knowadays learn second, third and even nth languages. The main difference would probably be colloquialisms unique to craftworlds and Commorragh, though Eldar pirates would presumably drop in on craftworlds every now and then to trade, and so these individual terms, while not found in the whole of Eldar society, would still be present on craftworlds if one looked for long enough.