I think that information may not be quite right...I dont believe there is a size difference in the Disney Princesses which were released boxed in their outfits. I think it was the build a pony ponies [Golden Delicious et all] which were slightly smaller in scale but then again I think there was a slight decreasing in the size of the line around this same time anyway so this may have been the whole line rather than just Disney releases - you can see it in how some of the accessories that came with the build a ponies dont fit as well on the earlier G3s [but its a minor difference]. There is a pretty obvious symbol difference - the Disney symbol is just a little less defined.
The second version of her is tougher to track down than the first version but both run to around the same price of $5