Surface elves are vaguely similar to drow in general outline, but have pale skins marred by ruddy spots on cheeks and wherever the sun has burnt them, and dark or colored hair. They are the traditional enemies of the drow. On the surface, they hold a terrible reign and try to slay any drow who vetures there, but because of their lack of discipline and strength they are only dangerous in large numbers.
All elves are to be sacrificed to Lolth as soon as possible. It is a sin to keep them around as slaves. But there is no great need to sacrifice them immediately - torture and severe treatment is always a good prelude. The danger lies in the extreme frailty of these slaves - they cannot stand even as much abuse as a regular goblin. Letting them escape sacrifice trough a mundane death is blasphemous!
Some people secretly keep elves as slaves for ages, and try to breed them or otherwise care for their health. This is fiendishly difficult. Even if kept secret and even when physically well treated, their souls seem to shrivel away to nothing over time.