Utility packaging serves only a single purpose and that is to ship your products. A standard brown shipping carton or an envelope would be considered utility packaging. While you can add your logo to utility packaging, the main purpose is to facilitate shipping.
Branded packaging places emphasis on the quality, look, and feel of the packaging. It is the canvas for your brand to showcase your values, mission and align your brand with your products. It can also hold information about the products, ingredients, and other information. This type of packaging is also an important marketing tool and adds value to your unboxing experience.