I do not edit in external editor.
When edit in iPhoto what exactly means: it create a modified version ? Seems the same way of working of Aperture, isn't it ?
The modified version will have the same size of original one or it's simply a file (little one) with changed version that link itself to original pic ?
That happens from iPhoto 2011 ?
When click on revert to original what happens: the version file is totally delete leaving only the original pic ?
It's quite similar to Aperture, but not identical.
When you edit with iPhoto the edits are recorded in the database. This is like Aperture.
However, when you edit a Preview of the edited file is created. You have no choice in this. This is for use in all the apps that integrate with iPhoto. This is different from Aperture. In that application you can decide not to have Previews or you can vary the quality of them.
Previews are also created if you import Raws.
Simply, there is no significant space saving in iPhoto 11 compared to earlier versions.
iPhoto has used non-destructive editing since iPhoto 08.
Reverting to the Original does exactly that.
If you don't use Previews then you could save disk space with Aperture.
However, if you don't use Previews you'll need to export from Aperture every time you want to anything with a phot - upload, email whatever.
Frankly, disk space is cheap. It's not a consideration when it comes to photos. Get a external drive. Either app can run a library from an external drive.
Something has changed withthe new unified photo library?
Reading here: http://www.apertureexpert.com/tips/2012/6/16/understanding-the-iphoto-93-and-ape rture-33-unified-library.html seems that now also iphoto with the new 9.3.x version has implemented the true non destructive image as Aperture does, is it correct?