If you're using Taxonomy to organize your articles, there are three different layout options for displaying articles associated with a given term or terms. These layouts are either set for an individual menu item or in Components > Taxonomy > Layout Configuration.
List Layout
The List Layout displays articles in a table format. The table shows the titles of each article, hyperlinked to the full text of the article. Columns showing the Created Date, author, and number of hits, as tracked by the system. A filter which the visitor can use to search the results can be displayed for menu items using this layout option.
Summary Layout
The Summary Layout displays articles in a blog-style format with the article title and the introductory text of the article.
Tree Layout
The Tree Layout displays a bulleted list of a subset of the terms on your site. Any children are shown as sub-bullets of their parent terms. These terms link to either the List Layout or Summary Layout to display the actual articles associated with a given term.