The "Queue directory" option specifies the location of the Postfix queue. This is also the root directory of Postfix daemons that run chrooted. See the files in examples/chroot-setup/ for setting up Postfix chroot environments on different UNIX systems. This option sets the "queue_directory" postfix variable.
The "Command directory" option specifies the location of all postXXX commands. The default value is taken from the "Program directory" option in Miscellaneous. This option sets the "command_directory" postfix variable.
The "Daemon directory" option specifies the location of all Postfix daemon programs (i.e. programs listed in the master.cf file). The default value is taken from the "Program directory" option in Miscellaneous. This directory must be owned by root. This option sets the "daemon_directory" postfix variable.