Difference between the 'field_read_only' and 'read_only' fields exposed by the Fields Meta Data API.

Difference between the 'field_read_only' and 'read_only' fields exposed by the Fields Meta Data API.

The API documentation describes the 'field_read_only' field to indicate that a field is read-only always, implying that no user can ever get the write access for this field.
The 'read_only' field's description states that its value can change depending on the user's permissions.

1. Am I correct to assume that, if for a field the 'field_read_only' field is true then the 'read_only' field must also be true and cannot change?
2. While using the API, I observed that for the 'Record Id' field (api_name: 'id'), 'field_read_only' is set to true, correctly indicating that it cannot ever be modified. However, its 'read_only' field comes as 'false' indicating that a user can modify a record's id. I was under the impression that if 'field_read_only' is true then 'read_only' must also be true. Can anyone confirm if my thinking is correct or is the value for 'read_only' is incorrect? I observed this for all the modules.