I am unclear as to the extent of a snapshot… does a snapshot preserve just the single document your currently working on or is it taking a snapshot of the entire project? Please explain the differences between taking a snapshot and a backup.
Snapshots only store the current text of the section you are editing. (If you wish to create a “snapshot” of the entire project, you should create a backup with the File/Back Up/Back Up To... menu command. This will create a duplicate of the project, optionally zip compressed into a single file, for safe-keeping. It should be noted this also happens automatically whenever you close the project; Scrivener will store the last five backups for you. You can alter how this works in the Tools/Options... dialogue, under “Backups”.)
Snapshots are more useful for setting milestones while you write, much like you might use save in something like Word. You can review the list of snapshots for the section you are working on in the Inspector pane. Click the blue ‘i’ icon in the toolbar, and then the antique camera icon at the bottom of this sidebar—or just go to the Documents/Snapshots/ sub-menu, where you’ll find some convenient tools and a shortcut that goes directly to this sidebar pane. Note that you can take snapshots of multiple documents at once if you select them all in the Binder first, and then use this menu.