Quick answer: Usually nothing. Coupon code, promo code and discount code all mean a code you enter at checkout to reduce an eligible price. The wording is a vendor habit, not a different product.
What each term usually means
A coupon code, a promo code and a discount code are all strings of letters and numbers entered in a box at checkout. If the code is valid and the items are eligible, the total goes down. Stores pick one word and stick with it, which is why you see all three in search results.
When the wording does matter
Three things are worth separating, because they behave differently:
- Referral codes link your order to the person who referred you. They may or may not change the price, so check the total.
- Automatic discounts need no code. The lower price is shown on the product page or in the cart.
- Membership discounts come from an account tier, such as a free member tier, not from a code.
What to look at instead of the name
The label on the code matters less than its terms: the percentage, whether it is sitewide or limited to eligible products, whether it is for first orders only, and its status. Our coupon table shows each of these for every code.
FAQ
Is a promo code better than a coupon code?
No. They are two names for the same mechanism. Judge a code by its percentage and its terms.
Do I need a code if a product is already on sale?
Not for the sale price, which applies automatically. A code may or may not stack with it, so test it in your cart.