See this article for more information: https://discodery.zendesk.com/hc/en-us/articles/360036783811
When creating a promo code, you can choose between the following "Types":
- A "Coupon" is a discount expressed in percentage (ex: 25%);
- A "Voucher" for a discount expressed in nominal value (ex: 25$);
- A "Product" is to simply gift one of your products.