How is it possible for two shaps to have the same perimeter but different areas?

Because the perimeter is the distance around the shape the area is the space inside so lets say I have two cakes. Both have a perimeter of 20 inches. on has two side with 8 inches wide, 1 inch length. so then you take 8 times 1 you get 8 inches2 that's the area. The other cake is 5 inches wide 5 inches length. Then you take 5 times 5 and get 25inches2