NU 15 Clean Disks Question

I''ve installed NU 15 on both a Win XP Pro 32 bit SP3 system and a Win 7 Enterprise 64 bit SP1 system where I periodically run the Clean Your Disks utility.  After finishing each run, the utility presents a final window with the button selections Refresh, Restart, and Continue.  My question is: what is the functional difference between Refresh and Restart?

 

-- Jim

 

PS - NU 15 does a pretty good job here cleaning up both the registry and the disks (with a minor tweak of the Firefox selections).