The superior tends to house a lot more items than the anterior mediastinum. It houses the great vessels SVC, brachiocephalic vein, origins of the brachiocephalic artery, left subclavian a. and left common carotid. What else does it house if nerves and viscera are the remaining categories?
As far as nerves go, it houses the vagus, phrenic and left recurrent laryngeal nerves. The viscera that it contains include the espohagus, trachea, thoracic duct, thymus, and lymph nodes.