Looks like Hasbro has updated their 25th Anniversary page. It has a thumbnail of each of the first 10 figures with their old file card images in place of the thumbnails with the new figure pictures, although they lead to the new figure pictures as expected. They also have the theme song playing when you view the page. You can check it out
here.
Edit: After looking up the old file cards I notice that the Baroness, Roadblock, Cobra Trooper, Scarlett, and Snake-Eyes have new art based on the originals or are slightly altered. I can not make out any differences between Duke's, Cobra Commander's, Storm Shadow's, Gung-Ho's, or Destro's.
Edit 2: The differences are as follows:
Baroness - New gun and now has a knife in left hand
Roadblock - Ammo strap added
Cobra Trooper - The strap on the right shoulder has different equipment to match the new figure
Scarlett - Crossbow is held up higher. It is now printed over her hair where as before it was printed over her shoulder.
Snake-Eyes - New gun that comes with figure
That is all that I could see at first glance. There are probable other differences but the pictures for the new art and the old ones I found are all small.
Edit 3: Dukes art is also new. The grenade on the left shoulder is smaller and the strap that holds his binoculars is different. My guess is that the art for all ten are new.