aab vs apk

APK (Android Package)

• It's the classic distribution file for Android apps.
• It contains all the app's resources (images in all resolutions, all languages, code for all device types, etc.).
• Because it's a single file, it's typically large in size.
• It can be installed directly on devices.

AAB (Android App Bundle)

• It is the new standard packaging format introduced by Google as of 2018.
• It includes all the sources of the application but is not a standalone installer.
• Google Play automatically generates optimized APKs (split APKs) by extracting only the resources appropriate for the user device from the AAB.
• For example: For devices with Turkish + HDPI screens, only those parts will be displayed.
• Reduces size (savings of 15–40%).
• The developer uploads AAB, the Play Store downloads APKs suitable for the user.

Current Usage (as of 2025):

• .aab is required for uploading to Google Play Store.
• As of August 2021, new applications are uploaded in AAB format, not APK.