I use "shorter" or "longer" for reach. For rise, I would be saying "higher" or "lower".

It's pretty straightforward why I went with a shorter stem when switching to drops. With the Bianchi's original flat bars, which had a slight sweep, my hands were a bit behind the center clamp. With any drop bars or bullhorns, my hands would be ahead of the center clamp. To adjust the position to me, the shorter stem brings the bars' center rearwards, putting the hoods basically in the same place that the flat bars' grips used to be.