Part of the order will be pre-ordered - This message will prompt if the customer add more than the available quantity to cart and part of their order is under pre-order. You can use :stock to show the available stock.

Pre-order limit exceeded - This message will prompt if the customer added more than the specified pre-order quantity. You can use :limit to show the pre-order quantity. To change the pre-order quantity, you can refer to this article.

Limits exceeded on cart page - This message will prompt in the cart page if you have any items that met the criteria of item 1 and 2.