jaustin,
Referenced ( machine reference point )/ Home / Machine Zero are typical names used to say that the user has defined to the controller ( Mach3 ) where 0,0,0 is. Until the machine is referenced the controller keeps track of movement via Machine Coordinates based on the controllers 0,0,0, but, once the machine is Referenced / a home location defined manualy, via switches or whatever........then the Home postition becomes 0,0,0.
The next item ........where is the Work / material / Part Zero ( Datum)?
That also must be defined to the Controller and the distance from Home to the Part would be a Work Offset, namely G54,G55, G........ G255 which is always the distance from Home to the Part datum and G54 is the default Work Offset
on startup.
So you could have numerous work pieces all with their owne datums.
The Datum point is specific location on the work piece by which the Gcode program is based.
Just some basics and hopefully will get you on track to additional reading about CNC as all this actually relates to how
someone is going to setup and machine a job.
RICH