In the context of these two industries, retail refers to the sale of products to its end users/consumers.
Consumer packaged goods (CPG) refers to a broad spectrum of manufacturers, sellers, and marketers of physical goods (typically packaged in some way, shape or form) used by consumers and sold through a retailer.
The easiest way to think of retail is anyone is selling to the end user, typically through brickandmortar retail stores, online ecommerce, or more outdated channels such as catalogs and phone orders. Popular examples of retailers include Walmart, Target, Amazon, Costco, and basically discount michael kors handbags every store you see at a shopping mall. Restaurants are also a form of retail since end users buy and consume the food to be eaten.
CPG is a broader space that encompasses companies one step earlier in the supply chain involved in the development, production, marketing, and selling of products targeted for end user consumption. Typically, CPG is involved at the wholesale level, so CPG companies are manufacturing the products sold to and that sit on the shelves of retail stores. Popular examples of CPG companies include Proctor Gamble, Johnson michael kors factory outlet Johnson, General Mills, and Clorox, all of whom have a huge portfolio of brands. CPG companies don necessarily need to be brands. For example, companies who produce packaged food products for restaurants may have no specific brand. But the companies are still manufacturing or selling packaged products used by consumers so they would be classified as CPG companies.
You can oftentimes find that CPG companies also have an element of retail. For example, fashion brands such as Gucci, Prada, or Dolce Gabanna are all technically CPG companies since their primary business is creating and selling handbags, oftentimes to highend retailers such as Barneys, Saks, and Neiman Marcus. However, they also have retail stores where they exclusively sell their own products (and also serve as a means to establish brand presence and engage their consumers).
So you can see, the lines between these two industries can oftentimes be blurred which is why they are so frequently referred to in conjunction with one another.