That is not necessarily true, even with 4 seats across on both planes. On the 777s, the seats are more sideways because the plane is wider than the A330 as mentioned by peasant. To say it another way, assume that the flight direction (facing forward) is defined as 0°, then the angle will be larger on 777 than on A330. As mentioned by correctioncx, the main difference is at the feet and the bulge (where the feet of the seat behind you protude near your shoulders). The feet space seems a bit wider on the A330 (because of lesser angle) and, hence, the bulge is more invasive. As on any of the J beds, the width varies depending on where you measure it.