Drupal versus Joomla

Que tal gente, mi nombre es Emiliano, soy nuevo en el mundo Drupal. Todavía no llegue a desarrollar nada con este CMS, porque generalmente he trabajado con proyectos chicos que podía resolver perfectamente con Wordpress.

Ahora quiero encarar algunos desarrollos más grandes y estuve investigando en el vasto mundo de los CMS, sin tener que llegar a un framework como CakePHP, algunos que permitan la "Extensibilidad" del mismo y he llegado a la conclusión de que las mejores opciones, por varios motivos, están entre Joomla y Drupal.

Has anyone seen the new Joomla showcase website?

Announcement
http://www.joomla.org/announcements/general-news/5233-community-showcase...

The Site Showcase, part of joomla.org
http://community.joomla.org/showcase/

It's community driven and has a lot of neat search features and categories. What does the new Drupal.org redesign have that rivals this?

Hi All,

in the company where I work we tried to use Joomla for our portals/websites, but we
quickly stuck with Joomla and mainly because it's a single website product and
anything multi-sites related cannot be implemented there easily. So, now we are
considering Drupal as a possible alternative.

I'm not familiar with Drupal so, I would really appreciate if could give me some
answer. Okay, these are my questions:

1. When we have multiple websites single Drupal code based, how is this organized?
   Is the code kept in single directories and other websites just have the symlinks