No worries. I would still consider these methods to be very different from each other. SPH, FVM and so on are methods to discretize continuum equations. If you have a continuum equation that describes your granular material you can use them and DEM kind of interchangeably. But often times such continuum equations do not exist for granular media or they break down in certain flow regimes. DEM on the other hand is not based on the continuum representation. Instead it is based on interaction forces that originate from particles being close by. While it might be possible to link these two, afaik nobody has done this, but I'm no longer active in the field.