The differences is, if you incepted system packages like system-ui, it will get origin com.nokia.maemo/local
And you CAN'T restore original package via simple command like: apt-get install --reinstall package. You need first download this package, for example:
apt-get install --reinstall -d package
And install via inception again:
/usr/sbin/incept /path/to/downloaded/package

If you will run origin fixer, you will change com.nokia.maemo/local to com.nokia.maemo. You need to do this only once. After this fixe, for reinstall any system package you can just run apt-get install --reinstall package, like it should be in the normal world.
Also if you need again incept some package after fixer its not a problem the origin will leave com.nokia.maemo instead com.nokia.maemo/local like without fixer