App Bundles are a publishing format, whereas APK (Android application PacKage) is the packaging format which eventually will be installed on device.
App Bundles use bundletool to create a set of APK. (.apks)
This can be extracted and the base and configuration splits as well as potential dynamic feature modules can be deployed to a device.
The dependencies can look something like this:
The contents of an App Bundle look kind of like this:
More information on App Bundles is available here.