The retailer is a business, person, or a shopkeeper, who buys a product and sell directly to the end-user consumer. They are basically, sellers who are at the end position of any business management system. They are the direct representative of the consumers, that is, they help manufacturers to know about the need and requirements of the consumer like those who work in shops or supermarkets.
The Wholesaler is a company that purchases services or goods for resale and maybe they resell them to retailers or shopkeepers.