Persistence Data Structures - Copy and Don't Copy?

The simplest persistent data structure would be a singly linked list. To scale this concept to any other data structure, you move from a list to a tree. All of the closure data structures that would be hash, hash maps or vectors are represented as trees. You only need to copy the path to the part of the tree that you're changing. As opposed to the entire tree. For instance, if you represented a vector as an array, you would have no hope but to Copy the entire array.