You shouldn't consider these things "sudo commands". Sudo is a command that enables users to run certain commands as root. Users in the "admin" group can run any command as root. But sudo can also be used to enable a user to shutdown the system, but nothing else, for instance. Remember that root can do anything in the system, which means that any user in the "admin" group can also do anything, including reading other users files or removing another user from the "admin" group.
You can read the full documentation for it here: http://manpages.ubuntu.com/manpages/oneiric/en/man5/sudoers.5.html