Use article indexes to identify articles from journals and periodicals. When you search an article index, you are searching bibliographic records that describe articles; you are not searching the actual articles. For many of the citations you retrieve in an article index, the database will also provide direct access to the article.
The key distinction between an article index and a full text database is that, in an article index, not every article you identify will be available online. In a full text database, on the other hand, all the articles are available online.
Article indexes will also contain records for other types of documents, such as dissertations, books, book chapters, conference proceedings, book reviews, and more.