An App ID is a two-part string used to identify one or more apps from a single development team. The string consists of a Team ID and a Bundle ID search strings, with a period (.) separating the two.
The Team ID is supplied by Apple and is unique to a specific development team, while a Bundle ID is supplied by the developer to match either the Bundle ID of a single app or a set of Bundle IDs of a group of apps.
Since most users consider the App ID as a string, they think it is interchangeable with the Bundle ID. Once the App ID is created in the Member Center, we can only use the App ID prefix that matches the Bundle ID of the application bundle.