Almost nothing special, actually - although the average developer in FAANG/etc. in my experience is considerably better than an average developer outside, that is in part because "the outside" is much larger.
I think the best analogy here is sports... there's a sharp pay cut when you go from playing in an NFL team, to not playing in an NFL team. NFL teams have N slots and they want the best players. That means that the N-th best football player modulo measurement noise is going to be paid much more than the N+1-th.
FAANG/etc. job count is not fixed and measurement noise is probably much higher (i.e. we can't actually determine which developers are best with that much confidence, and so I think a lot of developers could make it into a FAANG and do fine work there), but the same principle applies.
I think the best analogy here is sports... there's a sharp pay cut when you go from playing in an NFL team, to not playing in an NFL team. NFL teams have N slots and they want the best players. That means that the N-th best football player modulo measurement noise is going to be paid much more than the N+1-th.
FAANG/etc. job count is not fixed and measurement noise is probably much higher (i.e. we can't actually determine which developers are best with that much confidence, and so I think a lot of developers could make it into a FAANG and do fine work there), but the same principle applies.