Yes it's size but look at them all and compare them to Each other not your other breeds, drakes will be long with thick legs and set wider under their bodies ducks will be built short and squatty through the body think nerf football, thinner legs set closer together where the feet almost touch when they walk. Some pics may help after you get them off the roof.
So glad to hear you were willing to take them in, Angel wing is only looks nothing more and you can clip to make it look better and keep them from catching their wings on something. And if you have plenty of room you maybe able to keep all the drakes with out too much trouble, or are you planning on rehoming or eating some of them?
