What are the key differences between a binary search tree and an AVL tree in terms of their structure and performance?

A binary search tree is a data structure where each node has at most two children, and the left child is less than the parent while the right child is greater. An AVL tree is a self-balancing binary search tree where the heights of the two child subtrees of any node differ by at most one.

The key difference between a binary search tree and an AVL tree is that AVL trees are balanced, meaning that the heights of the subtrees are kept in check to ensure faster search times. This balancing comes at the cost of additional overhead in terms of memory and time complexity for insertion and deletion operations. Overall, AVL trees provide faster search times compared to binary search trees, but with increased complexity in terms of maintenance.