Shopping is a targeted ad channel. It’s only designed for physical products that can be bought in an ecommerce store. While other Google ads can cover anything from psychic healing to dog food, university education to industrial drills, Shopping ads only cover the sort of things Amazon might sell. (Admittedly, that’s a wide range of products!)
Unlike AdWords, Google Shopping results can display dynamic prices, images, reviews or star ratings and detailed information about a product. They’re intended to be local (or at least get the right country/currency) and encourage viewers to click and buy immediately.