su manual

<http://manpages.ubuntu.com/manpages/precise/man1/su.1.html>

> 
> The current environment is passed to the new shell.
> 
> 
> 

Obviously you cant use su in Ubuntu as in `su` but it has to be always `sudo su`since the root user is disabled in Ubuntu but it seems this changes the abilities of the su command.

Any explanation?