Service industry versus retail industry
As established above, the retail sector is a subset of the service industry, primarily because retail is about more than just purchasing an item. Retail largely revolves around customer service, such as helping customers choose products, offering a positive experience, and providing support after a purchase sale, such as returns and assistance with product-related problems.
The service industry, though, is much more than just retail services. It also includes transportation and distribution, restaurants, tourism, insurance and banking, healthcare, and even legal and professional services. Basically, if it doesn't directly make something or produce raw materials, such as food ingredients or iron ore, it probably falls under the service industry.