The water is hotter in a commercial dishwasher. I forget the exact numbers but it's substantially more. What the commercial dishwasher doesn't have is an "oven style" heating element running around the perimeter of the bottom (or somewhere thereabouts) to dry the dishes. Most residential dishwashers have this. This is why some dishes say "top rack only". The water coming out the top isn't any different. It's that you're moving the dish farther from the hot element. So a dish that goes through a commercial dishwasher sees higher average temp but substantially lower peak temp.