Another answer - 

You are a 

>! Burger :)

Explanation

>! **Layer 1** - *Cheese* with rough edges     
>! **Layer 2** - *Fillings/Toppings*. Often it's difficult to know what stuff's are included in a burger. They keep changing according to what kind of burger you are eating.     
>! **Layer 3 & 4** - *Bun* which serves same purpose    

Here's an example - 

>! [![enter image description here][1]][1]    


  [1]: https://i.sstatic.net/ZMqV8.jpg