When a task is attached to an activity in a project, some information are shared between them.
When a task is created from an activity, the title of the task will be the same as the activity.
Any editing of the title afterwards will not result in any changes between the two objects.
Start date and end date
When a task is attached to an activity, the star date and deadline of a task aren't editable. This is done to ensure that the tasks are controlled by the project timeline.
The time estimate can be changed from the timeline or the task.
This can be changed from the timeline or the task.
This field is useful as the project manager can see the progress of the project change, as the users of the task report new % values.