Not sure what the difference is between pieces, eaches, and CPQ? Sometimes this can be a bit confusing. See below for a full breakdown.
Pieces equates to pieces per each sellable unit. If it's helpful, think about a ream paper, a piece as related to the ream would be 1, but the each sellable unit would consist of 500 pieces of paper per each ream. Therefore, the pieces value would be 500 and the order unit would be Eaches. Note that when pieces is more than one, the storefront converts this to a package therefore the user when order per packages as the sellable unit.
CPQ stands for Case Pack Quantity, an example of this would be if there were 50 reams of paper of 500 pieces in each ream or sellable unit and is sold in cases of 50 reams per pack. Pieces would be 500 and CPQ would 50 and order units would be Cases. Endusers will need to order in multiples of 50 when adding their order quantity to the shopping cart.
Order Unit is by Eaches or Cases. Eaches is the sellable unit in increments of 1. Cases is the sellable unit determined in the CPQ field.