There is a difference between inventory items like stock and non inventory items like assets. In the case of inventory items these can be split further into consumables and saleable stock. So for commodity items and consumables within your inventory you need a single identity to cover each item type. You may also need a batch number B4567 to identify the batch in case of customer complaint. For example, if you are selling flour you will have a product code for flour, say P1234, but each consignment of flour that arrives will have its own batch number. For internal consumables like A4 paper however this is not necessary. For unique assets such as Laptops or phones you will have a generic code but also a barcode serial number so that each one can be identified uniquely. In this way you can easily see the number of laptops you have in total but if you need to search for a specific one you have its unique identity as well.