Yeah, I totally agree with what everyone else has said. No matter what they are, they are GORGEOUS.
I, personally, love the racier, sleeker look of the Mallards than the round, tiny look of the Calls. Not to mention, Calls are known for being loud. It is all relative as to which a person likes or dislikes.
As far as the differences between the two, Calls were simply bred to be slightly different physically and, of course, to have a loud Call. No, the White Mallard is not technically an albino, although sometimes people refer to it as such.
To me, the distinctions between the breeds of domestic ducks are not set in stone. All of them, for the most part, came from Mallards (except Muscovies). Some retain more resemblance to Mallards than others. Most of the current breeds though, with just a handful of exceptions, have been developed in the last 50-100 years by crossbreeding the various breeds. Because of that, to me personally, it wouldn't be terribly important to call them Calls or Mallards.