The Menus, Products and Services modules are all very similar in functionality. They each contain sets, tabs and sections.
Sets are the framework for setting up the information you wish to share -- not the actual information itself, but the base location where you will eventually add your menus, products and services. Sets are like storage containers that hold your tabs and sections.
Tabs are the easiest way to organize the information for your customers. Even though tabs are optional, they separate menu items like appetizers from desserts, products like shampoo from makeup and services like massage from tanning. Using tabs also helps make changes easier.
Sections share the actual information with your customers. Sections contain the individual menu items, products and services.