The laws of physics say they will drop at exactly the same rate. That would assume that all things are equal.(same speed,same wind drag etc.) The arrow with the higher f.o.c. should recover faster out of the bow, so it should drop less.
With crossbow arrows, many times the higher FOC arrow will stabilize faster out of the bow. The faster a arrow stabilizes, the less drag the vanes impart on the arrow. In theory, this should equate to a velocity advantage downrange and better trajectory.
I support all hunters, regardless of weapon or technique!