What is the difference between /usr/local/bin & /usr/local/sbin
/usr/local/bin is for programs that a normal user may run.
/usr/local/sbin is for system administration programs (which are not part of the core OS) that a local administrator may run. By default, a normal user does not have /usr/local/sbin on their path.
The information you seek is available many places, one of which is http://www.pathname.com/fhs/.