At a very basic level, hot products are more difficult to transport and handle simply because they are too hot temperature-wise for humans to hold and, depending on the item, could still be in the curing or cooling phase.
Items that fall into this category can include hot foods, plastics, metals, and others. They require special belting to withstand the high temps and move them along a conveyor system. In some scenarios, a special environment to cool or to maintain the heat, may also be needed.