There is very little difference in the seat, other than around the feet. As a point of reference at 6'2" i can raise my legs/feet unhindered by the foot box on the 777, whereas on the A330 i have to bend my knees slightly.

The only other consideration I would have is if you are in a seat towards the back of the cabin the older 777s in particular can really howl. The A330s, especially the new ones, are much quieter imo.