Promo codes and coupon codes are often used interchangeably, but they serve the same core function: offering discounts or special deals. Technically, "promo code" is more commonly used for online shopping and digital deals, while "coupon code" can refer to both online and traditional paper-based discounts. However, both terms describe a code you enter at checkout to receive a benefit, whether it's a price reduction, free shipping, or access to exclusive offers.