While some may haphazardly interchange the terms UPC and SKU, they are actually two quite different entities. They are both numeric-based codes assigned to products, but UPCs, or Universal Product Codes are standardized for business use and provide a product description that, once scanned, anyone could read. In contrast, a SKU, or Stock Keeping Unit, is a number assigned to a product by the company for stock-keeping purposes and internal operations.
The UPC code is affixed to a product wherever it is sold, remaining a constant throughout the product’s shelf life. Since a SKU is unique to the company, the same product would have different SKUs if sold by different companies, but they would have the same UPC.
Another difference is that SKUs are typically eight alpha-numeric digits, while UPCs are 12 digits, numeric only.
In conclusion, SKUs are for internal use, and UPCs are for external, or universal, use.