Rendering in controllers vs rendering in views

Hello,
can someone experienced please explain to me what are the main
differences between the `render` methods in `ActionController` and in
`ActionView`?
I mean: arguments, internal working, purpose, rendering "layouts",
what are the differences?

I am looking into this because i want to better understand what
`render` does with its block, and if it is different when passing a
block to `render` in a controller or in a view.

I would like to be able to do something like this, but so far haven't
been successful:

render "sublayout_of_the_application_layout" do
  render "sublayout_of_the_sublayout" do
    render "my_view_here_rendered_in_three_nested_layouts"
  end
end

Thank you.
Alexey.

I have already received responses here: http://railsforum.com/viewtopic.php?id=47996