here are many fruits and nuts which have a stone or pit inside which has a hard shell and encloses the seed inside and fleshy outer part. Such fruits are known as Drupe. While in some of them we eat the fleshy part and discard the stone, while in others fleshy outer part is discarded and the seed is edible. This way the tree does not expose the seed to the world. Examples of the first category are avocados, mangoes, peaches, apricots, and plums, etc. Nuts fall In the second category called Nuts which the world loves for their nutritional value. They are full of energy and minerals. Examples are almonds and walnuts. Some pictures of Drupe. Please note that pictures have been saved from the Internet for illustration purposes.
Drupe Examples: We eat outer flesh.
Apricot 
Avocado 
Mango
Drupe: Of which we eat the seed or nuts
Coconut 
Walnut 
Almond