Complete Binary Tree
According to wiki, A complete binary tree is a binary tree in which every level, except possibly the last, is completely filled, and all nodes are as far left as possible.
Example
Full Binary Tree
A full binary tree (sometimes proper binary tree or 2-tree) is a tree in which every node other than the leaves has two children.
Example
Perfect Binary Tree
A perfect binary tree is a binary tree in which all interior nodes have two children and all leaves have the same depth or same level.