MY_Controller vs. Foo_Controller

[eluser]pbarney[/eluser]
What is the functional difference between:

Code:

class MY_Controller extends Controller
...
class Admin_Controller extends MY_Controller

...and...

Code:

class LoginRequired_Controller extends Controller
...
class Admin_Controller extends LoginRequired_Controller

They're both extending "Controller", so what's the point of using MY_?

Thanks for any insight!

Peter