In addition both models feature an improved version of Titleist’s Active Recoil Channel technology in the sole creating more face flex particularly on low hits yielding higher launching lower spinning longer shots.
The Z 585 is slightly more forgiving and features a high-strength steel face insert in the forged clubhead for higher COR and ballspeed at impact. A new internal “speed groove” behind the clubface further enhances face flex across a larger area of the hitting zone for extra forgiveness on off-center hits.
However I’d say it’s unlikely that a new iteration of the Mini is coming any time soon. Modern fairway wood designs like TaylorMade’s M3 and M4 for example are so good and so long that former Mini players can simply find the right fit and most likely get the same or even better performance.