A part is purchased from a vendor or manufactured.
A product is sold to customers.
A part could be a single item purchased for resale, or a component used to manufacture an item for resale. Consider the following bicycle business:
- Some customers purchase individual items, such as wheels, spokes, seats, brakes, handlebars, etc. When you buy these items from a vendor, you are purchasing parts. When you sell the items, you are selling products.
- Some customers prefer to purchase completely assembled bicycles. In this case, the individual components that you purchase to build the bicycle are the parts, and the bicycle you sell to a customer is the product. You buy parts, and you sell products.
More than one product can be associated with a part, or if a part is never sold, it need not have a product association.