It isn't the Order of the Golden Fleece. I'm assuming, from looking at Felipe, Letizia and Queen Sofia that JC is wearing an order from Argentina. Felipe is wearing a red sash (while Letizia and Sofia are wearing light blue- another Argentine order?) and the same medal at his collar, so Felipe and JC are wearing the same order. JC is wearing the collar so he was probably given a higher or the highest order, while Felipe is wearing a lower rank of the same order. If the order Letizia and Sofia is another Argentine order (which I expect it is since getty has a close-up of it), I expect it is a lesser order.
The only limit to our realization of tomorrow will be our doubts of today. Franklin Delano Roosevelt