The Networks tab replaces the Placements tab from the previous interface, and gives you more insight into where your ads are running. In the Networks tab, you can see your ads' performance across different networks like Google search, Search partners, and the Content Network. When looking at how your Content Network ads perform, you'll see that the new interface divides Content Network statistics into two groups: Automatic placements are pages in the Content Network where your ads have been contextually targeted. And Managed placements are sites or specific URLs that you've singled out.
More info: Google AdWords blog