Parent and Child Pages
Under the old Plone system, all content was arranged in folders and subfolders. This meant content could be organised nicely, but it often meant in order for something to work you had to apply the change to the folder as well as the page.
In Drupal, we have the concept of parent and child pages (which you might be familiar with from the World Harmony Run site). Suppose you want to create a meditation section on your site, with a main meditation page and some other meditation pages leading on from that. If you set the main meditation page as the parent page of the other pages, then the other pages will exist under the main meditation page.
Clicking the Create new page link will, by default, set the new page as a child of the page you were on when you clicked the link, although that can be changed whilst editing the page.
Another advantage of this system is that you can move the pages from one place to another in the site. In Plone, the URL (the address of your page) was tied to the folder, so if you moved your page to another folder, the link was broken. However in Drupal, the URL is not tied to anything, so you can move your page anywhere in the country site. You can see the entire structure of your country site by clicking on the 'View/arrange pages' link, and change the entire structure in one go.
All the content that was on the old Plone site exists on the new site, and the same structure has been kept.
If you enable the 'Navigation' sidebar block, or the 'Navigation controls' options in the edit page, the parent/child structure can also play an important role in the navigation of the site.
You can also set the URL structure of a new page by unclicking 'automatica alias'