Unless I am misunderstanding the question, the way I would do this is to:

1. Create a relation between your original and updated layer.
2. Select all in the original layer.
3. Run the relate to pass the selection through to your updated layer.
4. Invert the selection
5. Export the current selection.

Unless I am misunderstanding the question, the way I would do this is to:

1. Create a relation between your original and updated layer.
2. Select all in the original layer.
3. Run the relate to pass the selection through to your updated layer.
4. Invert the selection
5. Export the current selection.