Quick Add: This allows you to add 1 or more URLs into your report without any additional custom data.
Add Articles: If you build more advanced reports with multiple categories and/or additional information that you want to associate with each article you can use the more advanced "Add Articles" button to include this information as you add in URLs one at a time. You can still batch add multiple articles here if you want to assign the same metrics, like Category, to multiple articles at once.