/bin: Stands for binary. This folder contains base executables which are required for minimal system working. These commands are available in runlevel 1 for basic administration. Commands which are available in /bin folder is accessed by every one and can run by every user. This folder contains basic commands such as cat, chmod, chgrp, chown, date, dir, dd, df, ln, mv, echo and zipping tools such as bzip, gzip etc.
/sbin: This folder stands for system binaries or super user binaries. This folder contains commands which are required for changing system properties or system level settings such as disk management, network management etc. This folder is accessed some times by normal user but they can not execute any of the commands located in this and what ever commands/scripts located in this folder are run only by root user. If you want to make normal user to run these commands you have to implement SUDO or Powerbroker to give elevated access. Some of the commands available in this folder are chkconfig, dhcpclient, fsck and its related commands, ifconfig and its related commands, init and its related commands, lvm and its related commands etc.