Difference between coupon code and promotion code
Promotion codes are a great way to save money on your purchase. The particular code you are offering to your customers will be applied by the customer when they reach the checkout page while subscribing plan or paylink.
Coupons will be applied by the admin for their customer in the invoice section.
As the admin adds a customer to their invoicing, they can choose to provide them with coupons, discounts or special offers. These will automatically be applied to the invoice, and can be adjusted or removed as needed. If you have any further questions please don't hesitate to let me know.