why Hoffman tree is not an AVL Tree?

[Vuhelper]

As we have studied, for a tree to be AVL, there are two conditions:
1) Tree must be Binary Search Tree
2) For every node, height of left and right subtree may differ by at most 1

For Huffman encoding, we also need a Binary tree to get the codes of characters. And we have different method to build that Binary tree.
Note that Binary tree used in Huffman encoding is not even Binary Search Tree.