Product is the term used in M3 for items included in a product structure.
Product refers to the superior item as described in a product structure, while Material refers to those items included in the superior item. In this connection, the terms product number, and component number are the same as item number.
An item can be both product and material, though not in the same product structure. As a product, the item is made up of other items (material). While as material, the item is included in other items (products).