What is the real conceptual difference between ui:decorate and ui:include?

Question

It occurs ago me that ui:decorate is functionally the same as ui:include except that you can also pass ui:param and ui:define

Answer 1

The main difference between and is that the is intended to allow insertion of user-defined template components, while the is intended to include an existing and already-predefined template.

This indeed means that the supports for user-defined template components in its body and can insert it at the place inside the template.

Here's a -somewhat clumsy- example to show where it can be used:

/WEB-INF/templates/field.xhtml

/page.xhtml

    
        
        
        
            
        
    
    
        
        
        
            
        
    
    ...

Note that it renders the components nicely in each cell of the panel grid. Again, this particular example is pretty clumsy, I'd just have used a tag file instead. Only if it was a larger section, e.g. a whole form whose e.g. its header or footer should be customizable, then an would have been appropriate.

Another major advantage of is that it allows you to use a composite component with a template. See also Is it possible to use template with composite component in JSF 2?