Relationships between Components, Modules and Plugins in mvc

[eluser]rogierb[/eluser]
In joomla:
A component is a larger functionality like a gallery
A module can be part of a component, like a module for showing the latest 4 pictures.
A plugin is something that can be used by components or modules (like a PDF plugin)

In CI, there are no components.
If you want to make the comparison, which would be like comparing a chicken with a car:
Joomla Components = CI modules
Joomla Modules = CI helpers
Joomla Plugin = CI plugin

But that comparison is as accurate as shooting the sun with a bb-gun.