Is there really a difference between the cheap and expensive foods? Why would I buy the stuff that costs twice as much as the cheap stuff if there's no difference?

The cheap dog foods do not have the vitamins & nutrients that are in the expensive ones. The cheap ones also uses nasty fillers. Be sure & read the labels they tell you all ingredients. You can also go to different websites & check out most dog foods.Consumer Search is a good one or just type in dog food, it will give you multiple choices for the best brands. They will even tell you brands that have been recalled & all ingredients.