An article displays content (text) and media.
Each article is link to a page and is displayed inside the context of this page.
In others words, linking one article to a page creates a context for this article.
Contexts are very important because they set :
Depending on the context (article linked to a news page, a description page, etc.), the display of one article can be different: In one case, the subtitle can be displayed, in the other case not and the article is used as a picture gallery container.
These various displays depends on your website architecture and your webagency certainly gave you a documentation of your website.