Commander, or Knight Commander, is a title of honor prevalent in chivalric orders and fraternal orders.
Insignia of the rank of Commander in the Legion of Honor
Grand Cross is the highest class in many orders, and manifested in its insignia. Exceptionally, the highest class may be referred to as Grand Cordon or equivalent. In other cases, there may exist a rank even higher than Grand Cross, e.g. Grand Collar. In rare cases, the insignia itself is referred to as the "grand cross".
Josef Graf Radetzky wearing the Grand Cross sash and star of the Military Order of Maria Theresa