Product Discount
A Product Discount applies a reduction to the price of a specific product or group of products in your app.
If you offer a discount on a particular product, say a t-shirt, the discount will only apply to that item when the customer adds it to the cart.
Order Discount
An Order Discount applies a reduction to the total order value, regardless of the products in the cart.
If a customer buys multiple items, the discount will be applied to the entire order. For example, a 10% off the total order amount.
Buy X Get Y
A Buy X Get Y discount is designed to reward customers for purchasing a certain quantity of items by offering them a free or discounted item as a bonus.
"Buy 1 t-shirt, get another one 50% off" or " Buy 3 items, get a free item". the "X" represents the quantity of products customers must purchase and the "Y" represents the reward they get in return.
Free Shipping
A Free Shipping discount allows customers to receive their order without paying shipping fees when they meet specific conditions.
"Get free shipping on orders over $50" or "Free shipping on all orders placed through the app".
Learn how you can configure each type of discount, reading this article.