Installing Android OS on SD card I am not using Android smartphone till now. I want to install the Android OS on SD card and use this SD card to boot Android on same line of smartphones.

Is it possible to do that?
I believe it is possible if your phone has an unlocked bootloader and you are capable of modifying it.  I have no idea how to do this but you may find help on Stack Overflow.  You can also check out how the devs that install Android on Windows phones do it.  This site talks about installing Android on the SD card for their dual-boot mod.

This is probably more work than it's worth.  Another option, if you are going to be using it on the same exact model of phone and they are rooted: Use Titanium Backup to backup all the apps and settings and then restore them to another phone.  This can be done to the SD or to Dropbox.