Xfconf is the new configuration system for xfce 4.6, it replaces the 'old' mcs-manager that came with previous versions of xfce.

Xfconfd is the daemon handling the storage of settings. Just like mcs, settings are stored in 'channels'.

Xfconf-query might be one of the tools many users have been waiting on for years. Especially those hanging around in our IRC-channel. Instead of having to guide new users through several dialogs and windows, it is now possible to have every control over your xfce desktop at your finger-tips. You can change any setting stored in xfconf with xfconf-query.

The following example allows you to set the wallpaper on your first monitor:

xfconf-query -c xfce4-desktop -p /backdrop/screen0/monitor0/image-path -s ~/path-to-wallpaper
xfconf-query -c xfce4-desktop -p /backdrop/screen0/monitor0/image-show -s true
xfconf-query -c xfce4-desktop -p /backdrop/screen0/monitor0/image-style -s 0

Xfsettingsd is an independent XSETTINGS daemon, it uses xfconf to read its settings from the 'xsettings' channel and then exposes these settings using the XSETTINGS protocol.

xfce4-settings is the front-end replacement for the mcs-manager, it comes with several different components for configuring application-independent settings inside xfconf.