App Catalog is a service that runs behind the scenes. It contains the full list of any Apps that can be added to SugarCRM instances. When new Apps are added, Catalog is updated.
SugarCRM talks to Catalog to find out which Apps are available for a user’s instance. It only returns a list of Apps which have already been approved by the Tenant’s Administrators.
Sugar App Center also talks to Catalog to find out which Apps should be displayed in the App Center, as well as which Apps have already been Authorized or not for the Tenant’s use.