Android InstallLocation

When we put the application into Google play, I want to know which one is good

>Having Android: installlocation = "preferexternal" or > without mentioning any location

What is the difference between versioncode and versionname in the following statement

android:versionCode="1"
android:versionName="1.0" 

Thank you in advance

resolvent:

If "preferexternal" is declared, the application is requested to be installed on the external storage, but the system does not guarantee that your application will be installed on the external storage. If the external storage space is full, the system will install it on the internal storage. Users can also move your application between the two locations

If you declare "auto", it indicates that your application may have been installed on external storage, but you do not have the preference of installation location. The system will determine the location of application installation according to several factors. Users can also move your application between the two locations

android:installLocation="auto"
    android:versionCode="5"
    android:versionName="0.5.02"