There are two totally different options available actually, depending on what you are trying to achieve. See this article for more details:
Basically though, the Refresh option is used to restore your Windows system to its default state, whilst preserving your data (but non-Metro applications are not reinstalled however a handy file is saved on your desktop that lists items that need to be reinstalled if need be). The reset option from what I understand, will wipe the data on your hard drive and then reinstall Windows.
I have only tried the Refresh option though, just out of curiosity...
Hope this helps!