To find the minimum absolute difference between any two distinct nodes in a binary search tree, you can perform an in-order traversal and compare adjacent nodes. 

During the traversal, you can keep track of the previously visited node (initialized as null at the beginning) and compare its value with the current node's value. If the difference between these two values is smaller than the minimum difference seen so far, update the minimum difference. 

Here's the code in Python:

```
class Solution:
    def getMinimumDifference(self, root: TreeNode) -> int:
        self.prev = None    # previously visited node
        self.min_diff = float('inf')    # initialize minimum difference as infinity
        
        def traverse(node):
            if node:
                traverse(node.left)
                if self.prev is not None:
                    self.min_diff = min(self.min_diff, abs(node.val - self.prev.val))
                self.prev = node
                traverse(node.right)
                
        traverse(root)
        return self.min_diff
```

The time complexity of this solution is O(N), where N is the number of nodes in the tree, since we visit each node only once during the traversal.
Data la radice di un Binary Search Tree (BST), restituisce la minima differenza assoluta tra i valori di due nodi diversi nell'albero.