If you use the "classic" quadrants, the only difference will be some extra ability possibilities on stellar objects and added abilities to the Gold system types that were nothing but pictures in stock SE4 (such as organic infestaions, which cause random movement and damage to your ships). If you use a FQM quadrant, there will be more moons and actual belts of asteroids (unless you select a "No AST" quadrant type). FQM adds many new options for quadrant types, including various relative levels of warp points and planet densities across systems. I'd recommend loading up
FQM (standard) and checking out a few maps.
The version of FQM included in Devnull is/was in dire need of updating.