The information reaching the aircraft from a VOR is the radial from the
station (QDR) encoded in the phase difference between the signals (that's what
the 9 is saying in the A9W designator). The RMI takes this and simply drives
the tail of the needle to that figure on the card and therefore the needle
pointer is over the QDM. If the RMI is slaving properly and showing the correct
heading then the orientation will be correct and the needle will also be
pointing at the beacon so you can see the relative bearing also.
However if it has failed the card won't rotate. So you've kept radial
information and lost relative bearing.
The NDB has no information on the signal (that’s what the 0 in the N0N
designator means) all the information is derived from the onboard equipment
which rotates the loop aerial together with the needle which is slaved to it until it gets the null in the cardioid. So now you can see that the needle will always
point to the station whatever the orientation of the card or the aircraft, so
relative bearing information is kept but radial information is lost.