You can create the following catalog items using the ACC:
folder - Contains any other type of item to form an organizational grouping. Folders appear in the ACC, but do not affect how users interact with your catalog.
catalog - Holds any number of other catalogs or categories; a catalog can be the child of another catalog, or of a category.
category - Can be either the child of one or more other categories or a root category. A root category is a starting point in the navigational structure of the catalog.
product - A navigational end-point in the catalog. However, customers actually purchase the SKUs associated with the product, not the product itself. A product can have several associated SKUs, representing different varieties, sizes, and colors.