The NIS Help pages say, "The 'Automatic Download of New Version' option automatically downloads the latest available version of your Norton product and prompts you for free installation." (Italics mine.)
But I have that option enabled (Windows 7), and after leaving my pc idle for awhile came back and was greeted with a prompt to reboot for my upgraded NIS (from v21 to 22) to take effect (I forget the exact wording). So it had not only just downloaded, but installed already. Doesn't that contradict what the help files say about prompting to upgrade? And what would have happened if I had that option turned off? Would I ever get any kind of notification that a new version was available, or would I always have to depend on checking manually for a new version? BTW, the unexpected install left me without an opportunity to make a record of my settings before some of them got changed, including my custom program rules in Firewall, which all got deleted (fortunately I don't create many of those anymore).
On a related note, if I disable "Automatic Download of New Version," automatic Live Update would still supply within-version updates from, say, NIS 21.5.x.xxx to NIS 21.6.x.xxx. Correct? I'm pretty sure than answer to this part is "yes," but thought it wouldn't hurt to double-check.