Excellent question! Article Builder produces high quality articles built around the topics and keywords that you give it. It's different from the old-style Private Label Rights (PLR) articles, though.
The old PLR gives every member the EXACT SAME ARTICLES. Even if they are high quality, they're not different at all! That's not good for ranking in the search engines -- even if you're only using the articles to build back links to your site.
Article Builder is different. Each article is built by weaving together snippets to build an article based on your category and subtopic choices. Since we have tens of thousands of categorized snippets in the database, every time you generate an article, it's different!