Recently I've read about namespaces and how they are beneficial. I'm currently creating a project in Laravel and trying to move from class map autoloading to namespacing. However, I can't seem to grasp what the actual difference is between PSR-0 and PSR-4.

**Some resources that I've read are...**

* [Battle of the Autoloaders](http://www.sitepoint.com/battle-autoloaders-psr-0-vs-psr-4/)
* [Laracasts PSR-4 autoloading](https://laracasts.com/lessons/psr-4-autoloading)
* [PSR-0](http://www.php-fig.org/psr/psr-0/)
* [PSR-4](http://www.php-fig.org/psr/psr-4/)

**What I understand:**

* PSR-4 does not convert underscores to directory separators
* Certain specific rules of composer cause the directory structure to become complex which in turn makes PSR-0 namespacing verbose and thus PSR-4 was created

Examples explaining the difference would be appreciated.