Explanation
Graphical user interface, application, Word Description automatically generated

Box 1: price group, affiliations
Price groups are at the heart of price and discount management in Commerce. Price groups are used to assign prices and discounts to Commerce entities (that is, channels, catalogs, affiliations, and loyalty programs).
Because price groups are used for all pricing and discounts, it's very important that you plan how you will use them before you start.
If you want to apply customer-specific prices, we recommend that you not set price groups directly on the customer. Instead, you should use affiliations.
Box 2: trade agreement, customer
Trade agreements are fixed price or discount agreements that are set up for one or more customers or vendors for the sale or purchase of single or multiple products.
Trade agreements can apply to the following:
A specific customer, a vendor, or a product
Groups of customers, vendors, or items
All customers, all vendors, or all items
Reference: https://docs.microsoft.com/en-us/dynamics365/commerce/price-management
https://docs.microsoft.com/en-us/learn/modules/configure-use-agreements-dyn365-supply-chain-mgmt/2-trade-a