A binary tree is a tree data structure made up of nodes, each with at least two children, known as the left and right nodes. The tree starts with a single node known as the root. The tree data structure made up of nodes, each with at least two children or even one child, is called a binary tree and except for the root node, each node will have only one parent.

In a full binary tree no node has only one child,each node has two children and full binary tree is a perfect binary tree with all leaves at the same depth.

on the other hand In a complete binary tree is like a perfect binary tree but with rightmost so many leaves removed.the attractive feature of a complete binary tree is that it can be represented in an array very efficiently.the binary heap data structure used a complete binary tree stored in an array.