Drow's have blue, paleblue or purple skin while Dark elves have tan, brown or dark. So I'd leave it to the portrait pack to name both.
Sorting DarkElf from Elf.... I'm not sure it's worth it. Their eyes have slightly different color ranges, but surely that's not a big deal. Maybe just work on adding sorting by skin tone, and leave that to sort them. Any DarkElf labeled with brown or dark skin color wouldn't be assigned to a normal Elf, because they never spawn with that skin tone.