What is the difference between pulse and live updates?

Hi I just want to ask what the difference between pulse and live updates. I read that the live updates check every hour when the PC is idle. Does that explain the the little box coming from Norton saying its performing background tasks while I'm idle? And are pulse updates the small definitions that happen when I check for updates. And also the small updates don't install themselves? Doesn't Norton say it automatically check and install updates? 

Sorry for the long post 

 

If if you need some extra clarity just tell me and I can tell you what I mean