Unit of measure
A unit of measure (UOM) is the unit in which the item is packaged. For example, you order soda pop by a single can, six-pack, two-liter bottle, or a case--each of which is a unit of measure. When you define items in Inventory Control, you must define at least one unit of measure per item.
Stock unit of measure
The stock unit of measure is the UOM in which you track inventory balances. You define all valid units of measure at the Item Group level, then define a stock unit of measure for each specific item.
Alternative unit of measure
Alternative units of measure are valid UOM that are defined for items. You define alternative units of measure to account for different UOM used during purchasing or sales of an item.