internal SD card and external SD card ...now what are those
external SD is your micro Sd card.
the total phone memory is divided into 2 parts
1) phone memory ( usually 1 gb or less )
2) internal sd card ( remaining memory )
so a typical 4gb phone is divided like this
phone memory - 800 mb
internal sd card - 2.5 gb
before android 4.1 there use to be only phone memory and micro sd card..
so if you installed an app it will install in phone memory and you could move the application data to micro sd card..
app2sd
but after 4.1 google introduced internal sd card.. what it does is fool apps into believing that micro sd card is actually internal sd .. so the apps still install in phone memory but transfer its app data to internal sd card .. so the total app + data still remains in phone memory ... and hence not transferable to micro sd card..
it was just introduce to stop people from transferring there apps to micro sd card..
in simple words its just a partition .. like you have c: and d: in windows..
that's why the app2sd does not work...
so in order to transfer apps to sd card after 4.1 we can only swap sd cards..
so if you have a 4gb phone with 16gb microsd card
before swap
internal phone memory - 800mb
internal sd card - 2.5 gb
external sd card - 12 gb
after swap
internal phone memory - 800 mb
internal sd - 12gb
external sd - 2.5 gb..
so once again it fools apps