Projects - When you restore a project, a new project will be added to the workspace. All tasks, comments, files and custom fields will be restored as well.

Tasks - When you restore a task, a duplicate of the task will be created in the related project. All comments, files and custom fields will be restored as well.

Comments - When you restore a comment, a duplicate of the comment will be created in the related task.

Files - When you restore a file, the file will be added to the related task.

Custom fields - When you restore a field, a duplicate of the field will be added to the related project. All field values of the existing tasks will be restored as well.