First is geometry, of what you are making.
it stands alone as data defining something.
IT alone cannot run a machine.
Only define the completed object.
All the CAD formats, iges, dwg, etc.........
Second are the motion commands in serial data.
another whole bunch of software to compute motion to the geometry.
Motion is Gcode, Cad is geometry,
So 2018 mcam motion will not transfer? but the Geometry will.
Motion created usually will not go "older" nor cross platforms.