The frequency analyser showes the frequency spectrum of the source,
either separately for both channels or together.   Roughly speaking
the XY scope draws a plots where the left channel is used for the
x axis and the right channel for the y axis. Thus a audio signal
only present on the left channel produces a horizontal line, whereas
a audio signal only present on the right channel produces a vertical
line.  Can be used as a PC-Based RTA.