Yes, ingame, both the allied race and NPC type use the same idle animation. WoWhead just wasn't able to adapt it yet. According to Perculia, they're working on it.
To me, the allied race version looks like the npc version's daughter. I don't particularly mind a younger long for Nightborne, but for me, their main appeal is their kind of aged, gaunt and regal beauty. The more slender faces, with high cheekbones and which are somehow also smooth and unblemished added to that idea. The more narrow eyes as well.
The allied race version is almost the exact opposite. The facial features are surprisingly round, the eyes are wide open and they do actually have those wrinkles and laugh lines. All faces have those for the females, I think. Whereas the NPC faces are surprisingly smooth.
It might just be my perception, but the NPC Nightborne's head seems more long and slender, while the allied race model has a bit more of a Blood Elf look to it.
Honestly, this could mostly just be my own perception, and once they fix the eyes, they will look almost identical, but I feel like more changes need to be made aside from just fixing their eyes. I know for sure, though, that I want one face for the female without all the wrinkles near the lips or nose. I know that kind of counteracts my claim that I want them to look more aged, but as you can see above, even without the wrinkles, the NPC version looks more mature.
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I tried to (badly, don't laugh at me) work the NPC Nightborne eyes onto the allied race face with photoshop. It was a bit rushed, but..
It does immediately change the whole look, as was already obvious, but I still feel like something is wrong. (or rather, not quite right..)
However, I couldn't find an allied race Nightborne model with the same gaunt facial features as the npc one, so maybe it'll look a lot better on on a player Nightborne with that face texture.
I still would like those lines around the nose to be less prominent on the player version, though.