There are typically a lot more ingredients in detergent, so YMMV depending on a number of factors, including the composition of your dishwasher (corrosion), how well you clean the dishes before putting them in (a few drops of Dawn isn't going to penetrate 3-day-old melted cheese), how much you care about disinfecting (bleach), etc. See https://en.wikipedia.org/wiki/Dishwasher_detergent#Compositi...