Answer:
Because they both produce natural but often unusable contents.
Explanation:
Freewriting is a form of prewriting strategy in which an individual writes without considering the rules of writing and style specifics during the writing process.
On the other hand, Automatic writing is a form of writing in which an individual writes without being conscious of what is being written.
The similarity in these styles of writings can be felt in their outcomes, in which they "both produce natural but often unusable contents."
Note: Freewriting and Automatic writing are not the same, they can only be used in the same context because of what they produce which tends to be similar.