What's the differences between Cart offer and Product offer?
A cart offer will be shown on the cart page when the customer clicks on the Checkout button.
A product offer will be shown when the customer adds the triggered product to the cart (only support ajax carts).
A cart offer will be shown when the triggered product is added to cart (it could be all product, specific products or specific collections), while the product offer is shown immediately after the triggered product is added to the cart right on that product page. In case the offers aren't shown on either page, check the guide for Cart offer and the guide for Product offer.
If the customer accepts a cart offer, the offered product will be added to cart and the customer will be taken to the checkout page immediately to process the order.
In case the offer on the product page is accepted, the offered product will be added to cart and the customer still stays on that product page to continue purchasing.