How are sections and categories different?
Sections are exclusive. Every article is associated with a section. An article cannot reside in more than one section.
A newspaper web site might have sections named “Politics”, “Sport”, “Weather” and so on.
Categories are a looser way of organising articles. An article can have up to two categories, and may have none. Categories may cross Section boundaries – that is to say, articles from several different sections can belong to the one category.
Following the newspaper example, categories might be used to organize articles into “Local”, “National”, “World” and so on.
Categories can be used independently (to list articles from all sections in the National category, for example), or combined with sections (to list articles in section Politics with category World).
For a more detailed explanation of how Textpattern organises content, read I’ve installed Textpattern. Now what?