What's the difference between "filling" and "topping"?

Native speaker’s answer
Rebecca
A "filling" is something you put inside something to "fill" it and usually has an opening to put things in or is enclosed. A "topping" is something that goes on top of something. Ex: The filling of the pie was too sweet for me. Ex: There were so many topping options for my pizza! I didn't know what to choose. Ex: I put some berries on my yogurt as a topping. It was delicious. Ex: I filled my sandwich with lots of cheese.