Great observation.
Your right, the 4e extended verandas, located where the bump outs end for the veranda extensions, and where the outer skin starts, are bit smaller than the cabins not at the end of these.
This gap occurs twice forward every 6 cabins and once aft. Times two if you count both sides of ship.
Exterior labeled photo;
http://www.disboards.com/showthread.php?t=2586763&highlight=dream+special
The balconies with the curved rails are the ones with a bit less sqft.
These include 5532/5534, 5544/5546, 5656/5658, and of course their sisters port side.
photo link again;
http://www.disboards.com/showpost.php?p=39847383&postcount=94
These said pairs also have less length/depth to the veranda partition, perhaps making them less private, however appear to offer improved view.
I always was curious if said veranda pairs connected thru the partition.
Never heard back from anyone.
HTH