I often see a forum post asking about the difference between sections and categories. It can be confusing, especially for someone who has Joomla. Joomla uses the same words to mean completely different things. I'd like at least attempt an explanation, looking at it in a couple different ways.


But if you've ever used Joomla please start by forgetting you've ever heard of it.


From a Design Perspective
Sections are a hierarchical organization system. Every node (article, section, static page, etc.) lives in a section. There is one special node which doesn't have a parent, and that's the root. Every other node has a parent. Permissions, styles, navigation items, and layouts are all assigned by section. We have a widget that displays the section hierarchy in a javascript-expandable view.


Categories are a hierarchical organization system. Every category has a parent, which can be another category or a section. You cannot assign permissions, styles, navigation items, or layouts to a category. On a category list page the style and layout come from the section to which the category belongs. We have four different category widgets, but none of them display the section hierarchy. Yes, we know we need to do that, but it hasn't been a high enough priority yet. Think of categories as a loosely structured tagging system.


From a Practical Perspective
I think in terms of drilling down vs. browsing. When I drill down on a site, I know within reason where I'm going, and I go straight there. That's how sections work. I expect section structures to be the most obvious way to structure your content.


The categories were intended to, in Don Kuramura's words, promote discovery. That's browsing. When I browse a site, I expect to click on a link which leads to something else with an interesting link, which leads to another interesting link, and so on. On a really good site, I can click on interesting links until I get sleepy or hungry. That's categories. So categories can be anything that your users might find interesting. They are there to pique interest


So that's another way to think of of it. You organize by sections and add interesting links by category.


An Example
If it's a game site I would expect sections like WII, XBOX, PS2, etc. You might want to have subsections, so you could have
WII
RPG
Driving
Sims
etc.
XBOX
RPG
Driving
Sims
etc.
etc.
Categories would be things like “Favorites”, “Classics”, “Adventure”, “Family-friendly”, etc.


Another Example
Think of a pet site. I would expect something like
Dogs
Retrievers
Setters
Pointers
Herding Dogs
Protection
Minatures
etc.
Cats
Long Hair
Short Hair
Medium
Hairless
Birds
Parrots
Parakeets
Falcons & Hawks
Other
etc.
Categories would be “choosing a vet”, “medical issues”, “Good for children”, “Show”, “breeders”, “end of life”,etc.

Another Example
Let's build a video website. We'll have a section for children's videos, one for grownups, and one for adult content. We'll provide the children's section free, the grownups section will require membership, and the adult site will require a paid membership. So the site structure will look like
Family-Oriented
Comedy
Animated
Television Characters
Adventure
Religious

Members
Comedy
Adventure
Romance
Thriller
Military
Classics
Adult
I have no idea how this would be organized. If I did I wouldn't brag about it.
Categories would be things like “Academy Award winners”, “Academy nominees”, “Disney”, “Crowd favorites”, “Sean Connery”, “Rat Pack”, “Brat Pack”, “30-something alums”, (Imagine your moderators are Bill, Cheryl, and Steve) “Steve's favorites”, “Cheryl's favorites”, “Bill's Favorites”, etc.


Summary
Ultimately these are just tools. I would suggest you start by organizing your content in whatever way feels natural. That will include
  • Do you want to limit access to parts of the site? If so that will define the highest-level section layout.
  • Do you want parts of the site to look different? Because style and layout are based on section, that will also define the sections.
  • What feels natural? If there is a way that would seem intuitive or expected by your users, that's the section layout.



Once that's in place you should ask yourself what other ways someone might want to look at or find content. Those are your categories.


Hope that helps.