APK is the acronym for "Android Package", which is a package file format most widely used by the Android operating system for distribution and installation of mobile apps.
XAPK is another Android application package format used on the Android operating system to install mobile applications. It's somewhat similar to the APK format but also different. Simply speaking:
XAPK file = APK file + APK expansion files (OBB file)
APK expansion files are used as a solution for the 100MB app size limit in the Google Play Store. If an app is larger than 100MB (which is quite likely for a big game), the output package will be split into the main part (APK) and the expansion files (each file can be up to 2GB).
Since XAPK contains so many complicated files, it is harder to install and can cause a big headache if you don't use a handy tool. But now you can install any .APK and .XAPK file via 9Apps APP with one click !!
Step1: Download the .APK or .XAPK file you need to install, you can download almost all the APK & XAPK you want on 9Apps .
Step2: Download and install the latest 9Apps APP for Android.
(Tips: you need 9Apps v188.8.131.52 or later for XAPK support)
Step3: Open 9Apps APP => switch to the TOOLS tab => click the XAPK button => You will see all APK / XAPK files on your phone, click the install button to complete the installation, it's that simple!