Yes, they are different data structures and thus will have a different memory footprint. In your example, you are comparing the memory usage of a scalar to the memory usage of a list which contains 4 scalars ($list[0], $list1, $list2, $list3). The point I'm making is that you're comparing apples to oranages...

I don't mean to be harsh, but perhaps you should peruse Which bad behaviour most deserves an electric shock? while paying specific attention to Re^2: Which bad behaviour most deserves an electric shock?.