Both WordPress (WP) and Drupal (DP) use databases to sort the content of a site. Here’s a summary of how it works.
Drupal says, “If you want to add a static page, like a Contact page or an About Us page, use a page.” You can add to and edit this page, of course, but it’s not a list of things, it’s just a document, a page. You probably won’t be using/adding too many of these often.
(WP: Posts, DP: Stories) Posts/Stories are entries that are part of a collection of entries, all organized under a category. For example, “Reading at Borders” would be a post/story and should be under a category called Events (or under Readings, a sub-category of Events). You’ll probably be using this most often as updates should be posts.
Categories keep the posts organized into sections. In WP, you can create new categories by going to Manage –> Category –> Create new. In Drupal, go to Administer –> Categories and create a new “vocabulary” (their term for category). You can also create sub-categories (Drupal calls them terms). An entry (post/story) can have more than one category, for example, I made this post under the categories WordPress, Drupal, and FAQ.