In the Realms, there are two (or maybe three) kinds of half-elves mentionned.
Half-surface elves. Standard half-elves. Their human parent can be any human; and their elf parent can be any surface elf, this change nothing. Stat-wise, exactly like the standard half-elf, except for size because it's FR. The thing that change (hair, eye and skin color) depends on the parent but don't affect any number.
Half-dark elves. A half-drow is exactly like a standard half-elf (except for his greyish skin and whitish hair) but has darkvision 60 ft. instead of low-light vision.
Half-sea elves (that's the one I'm not sure they're mentionned at all). They are roughly like standard half-elves, but maybe they got one thing more (related to water) and one thing less.