Install SD Card Vs Phone memory? and why the size of the app differs?

Question

I am bit confused about memory sizes in android apps, is there any difference between installing the application in Phone memory and SD card. I guess there might be difference of responding and running speed. But i am wondering is there any other differences in that.

And also i installed my application in Phone memory and again installed in SD card also. The immediate difference i can see is the size of the app.

While installed in Phone Memory :
Total size : 5.15 MB
App size : 4.96 MB
Data : 192 KB

While installed in SD card :
Total size : 3.15 MB
App size : 2.96 MB
Data : 196 KB

My Actual Size of the apk file is : 2 MB.

Why the above difference with phone and SD card installation.

I am really confused about these size variations. Where is app 2 MB and data 4 KB goes as the difference.

I googled a lot and failed to find the answers. I tried in developer.android.com and stackoverflow also, but i am unlucky.

So my doubts are,

1. What are the differences between installing an app in phone and SD card.

2. Why the size difference shows when i install my app in SD card and Phone. Where is the difference 2 MB goes and What is that difference.

3. How the size is more when installed from the actual apk. (My guess is , the apk will be extracted and installed in the device, so the sizes might be increased while installing.) Please correct me if my guessing is wrong in the 3rd one.

Thank you in advance.

Answer 1

Google has some info on the subject about difference on having app installed on SD card and internal memory here and on google blog. They are good reads and contains info about what types of apps that shouldn't be stored on the SD card.

The primary reason some apps shouldn't be installed on SD is that the SD card can (on some phones) be removed at any time by the user and thereby causing issues.