Both nutmeg and mace come from the same plane. Nutmeg is the 'nut' , while mace is the surrounding lacy 'aril' . Mace is separated from the nutmeg shell and dried until it's colour turns amber. Mace is sold either in blades or ground.
It adds a mild nutmeg flavour to soups and sauces as well as sausages, pates and and fish dishes.