I assume you mean how is %%this_fullname%% different to %%page_fullname%%?

'this' refers to the page containing the ListPages, while 'name' refers to the page being listed. In live templates, 'this_fullname' and 'fullname' are the same. In ListPages, they are not except if the current page is itself being listed.

The main reason for the 'this' variables is to allow construction of URLs back to the same page.

I think it uses created_at as the commented_at value, in that situation.