Logic 10.1 Saving "File" vs Saving "Alternative"

Logic 10.1 has a new "Alternatives" option. I can't figure out why, and what's the difference between saving "File" vs saving "Alternative"



From Apple's online manual:

Logic Pro X: Use project alternatives and backups

When Show Advanced Tools is selected in the Advanced preferences pane, you can create alternative versions of a project, each with a unique name and different settings. Alternatives are saved as part of the project, and share the same assets. Alternatives for the current project appear in the File > Alternatives submenu.



Each time you save a project by choosing File > Save (or pressing Command-S), a backup of the current project alternative is saved (up to ten backups per alternative). In the Project > Revert to submenu, backups for the current alternative are listed in descending order from newest to oldest.



Create an alternative version of a project

Choose File > Alternatives > New Alternative.



Enter a unique name for the alternative, then click Done.



Edit project alternatives

Choose File > Alternatives > Edit Alternatives.



Figure. Edit Alternatives dialog.

In the Edit Alternatives window, select an alternative from the list, then do either of the following:



To rename the alternative: Click Rename, then enter a new name.



To delete the alternative: Click Remove.



You cannot remove the Main alternative.



Click Done.



Choose a different alternative

Choose File > Alternatives, and choose a different alternative from the list.



If you have made changes after you last saved the current alternative, a Save dialog appears, so that you can save your changes in the current alternative before switching to a different alternative.



Choose a different backup of the current alternative

Choose File > Revert to, and choose a backup from the submenu.



In the Revert to Backup dialog, click OK.

Logic 10.1 Saving "File" vs Saving "Alternative"