Made-to-order means once an order is placed it needs to be made from start to finish. Once that is complete the item can be packaged.
Pre-made means they are already made, making them immediately ready-to-ship. When an order is placed the only task is packaging.
Notes: For the collection Made to order there will be a description: "Made to order - High quality". Apart from that, the product goes into the Pre-made category.