I think green jem is slightly more potent than purp, but I prefer the purp for the exotic smell/taste.
So far with my Jem grow the Mossy original Jem is a more indica whereas the the JD is a little taller with thinner leaves.
One of the mossy's is showing purple preflowers and the one of the Jd's is showing pink, the rest are green so far but they are only just going into flower mode.