Moving app between _three_ possibilities for storage?
System memory, internal memory is a mis-leading thing, its actually referring to storage space which is a very different thing to the meaning RAM often referred as memory!
The reference to storage - system as in /system would be more accurate.
When you download an app from the Play Store, it must be installed into the /data.
From there you can actually move the app to the sd-card. On stock vanilla android, the option is there 'Move to SD card'.
Now by the sound of it, its as if it is indeed moving the app to the SDCard, but its not really a SDCard, its how an internal storage space (think of USB flash drives), is treated as an /sdcard but in reality, you have internal and external storage, the latter being the actual micro SD card slotted in place.
Its a bit confusing how it works, from a developer's perspective, when a check is carried out for an SD card, Android seemingly &quot;tells&quot; the developer that the internal storage is treated as an /sdcard.
Also, to compound confusion even more, there's also a symbolic link to the real sdcard, /external/sdcard as well - this bit is dependent on what device/manufacturer is in question.
Yes, this is the expected behaviour, whichever storage (from a view point of Android and the hardware device's file-system priority, is treated as &quot;sdcard&quot;).
In short, nothing you can do, apart from using App 2 SD, but then again, that could fall into the same trap as I mentioned previously about the developer's perspective.
Edit
After the OP has edited their question to include the device, after looking at GSMArena
MEMORY      Card slot microSD, up to 32GB
Internal    1 GB storage, 384 MB RAM

Yup, it looks definitely like as if the internal storage is treated in this fashion as an &quot;SDCard&quot;...
The naming is misleading. What is really meant, is: internal (phone) storage 157MB, internal SD-Card (eMMC) 1024MB