[andrewg]

It's the wing loading (max takeoff weight / sqft of the wing). The 747-400's is something like 155 lb/sqft vs. 124 for the 787-8. In general, the higher the wing loading the better the ride.

[t0mas88]

In general yes, but the 777 and 787 have a system to automatically move the inboard aileron to reduce the impact of turbulence.

[sho]

I concede this is ridiculously pedantic, but the system you're talking about is called "gust supression", and uses the flaperons (not the ailerons) in coordination with the elevators. The ailerons are only used for turning and are so far out that trying to use them for altitude control would probably just move (and stress) the wings.

It's a very cool system though!