When speaking of the top free and/or open-source Content Management Systems (CMSs), two names (amongst others) that inevitably come to mind are WordPress (WP) and Joomla. While most people would associate WP with blogging and Joomla with standard websites, both CMS platforms are based on PHP, capable of building any kind of site desired, have a thriving and large user base (WP has ~28% market share, while Joomla is used by some of the largest multinational conglomerates) as well as a large and thriving developer base (thousands of add-ons for both).
It’s come to the point when you can integrate WP and Joomla to serve up different sections of the same website – or seamlessly transfer from one CMS to the other. But even though both WP and Joomla are very similar in utility and functionality for end users, for add-on developers the two platforms could not be more different – and that difference is what this post seeks to establish.
Plugins and Themes are logically separate in WordPress
WP has a fairly simple separation between the 2 kinds of add-ons it recognises; namely, Plugins for content, and Themes for presentation. There is a level of overlap between the two (Themes can include function.php that acts as a plugin and Plugins can influence how content is presented), but by and large, Plugins are Plugins, Themes are Themes, and are independent of each other.
In contrast, while individual Joomla extension types are clearly distinguished from each other (as explained below), a particular feature addition may have its functionality split up between various types of extensions, and extension packages give you the functionality of any number and types of related extensions in one easy-to-install unit.
There are no clear distinctions between (categories of) Plugins in WordPress
Aside from WP’s Core system, Plugins do everything there is to do with content management and manipulation. WP defines them as tools to extend the functionality of WP. There is a subset of Plugins called Widgets (which are more or less equivalent to Joomla’s Modules) – but they are Plugins nonetheless. As such, a Plugin can be as simple as a file uploader or as complex as an entire file management or e-commerce system.
Joomla extensions, on the other hand, are clearly separated by function, purpose and scope. All Joomla extensions are one of a few defined types (component, module, plugin or template); there is no generic ‘extension’ that does not also fall into some subset.
WordPress has no specific architectural paradigm that Plugin writers have to adhere to
In fact, WP plugins are exceedingly free-form. Want it class-based? No problem. Don’t care for classes? You can write a classic procedural Plugin instead. Want to set up MVC? Sure – in fact, there are already Plugins there that set it up for you. Don’t care for architectural patterns? Don’t need them. Want to write a Plugin that doesn’t use any WordPress APIs at all? Well… you could, although you might not like the overall experience much, and it’s highly discouraged.
You will have noticed at this stage that the difference is not so much in what Joomla extensions do vs. what WP plugins do, as it is the different approaches that WP and Joomla take towards the whole ‘content management’ issue. And it shows right where you’d expect it to, in the way you extend the core framework of both.