I've read that they do have different sugar profiles but have never confirmed this myself. Apparently some use simple sugars to get the fermentability a little higher and others don't. My vote is to find out which one you like better and stick with it.
On deck - AAA x2, Irish red
Primary - Baltic porter, IIPA, Mild, ESB, Milk stout, Scottish 80
Secondary - American Barleywine
Bottled - Gingerbread ale, IPA, Brown porter, RIS, Better than dead x2, APA x2, Kolsch