Chris Scott:
"The classic example are the A340 and A330 wings, which are - I believe - basically identical. But the A330 wings don't enjoy as much bending relief outboard."
Yes, that is true for the EIS versions. Apart from the local structure at the engine mounts the structure is identical. Basically the additional bending moment relief coming from the outer engines allowed the increased TOW required for the A340 range requirements.