SGTS stands for 'Staff Sergeants' and NCOS stands for 'Non-Commissioned Officers'. Both terms refer to a rank in the military. Staff Sergeants are the fourth enlisted rank in the United States Army, Air Force, and Marine Corps, and the fifth enlisted rank in the Navy and Coast Guard. Non-Commissioned Officers are military personnel who have not been given a commission, but still hold a position of authority within the military. They are typically responsible for leading and managing enlisted personnel.