Lightroom auto save

Lightroom only "saves" a photo when you first import it into the app. After that any changes that you make to that image are stored only in the local and cloud catalogs, the original image is not changed at all. What also happens is that Lightroom will add a reference to the image in the appropriate special albums (such as "My Edits" and "Unedited") that have been auto-created, but these are virtual lists created for the user's benefit. But they are just lists, they do not contain separate copies of your image files.

So if you edit a previously unedited image, that particular image reference will be removed from the "Unedited" album and added to the "My Edits" album.