What's the Difference Between a Coupon and a Promotion?

A promotion is a discount that can be applied to a product, collection, or store. You can give all customers access to a promotion, or limit access to specific customer tags, or club levels. When a promotion is applied, all customers who are eligible to receive the promotion, will automatically receive it. They do not have to apply it on their own. 

A coupon creates a discount that can be applied to a product, collection, or store. You can give all customers access to a coupon, or limit access to a specific customer tag or club level. To receive the discount, a customer must activate a coupon by entering a coupon code in their cart. They must apply the coupon code on their own in order to receive the discount.