These cans must be bigger on the inside!

This is like something out of Doctor Who, these cans of soup must be bigger on the inside than they look on the outside, just like the TARDIS! One can states that its 30% bigger and the other states that its 40% bigger and yet, both cans are the same size. Is this science in action or just the soup maker trying to fool us into thinking that we are getting a good deal. For more stuff like this go to the Picrail website.