The difference between the two is the P is a normal drive, the H is a Lightscribe unit. The P will be out first, December in Europe, and run about 30 pounds. The H will come out in early 07 and cost more due to the lightscribe tax. In any case, the difference in cost between these and the 16x models should be pretty minimal.
The specs are about what you would expect, 20x single layer burning for +/-, 8x dual layer slower for RW. CDs are burned at 48x and lightscribe is burnt at 1.6x should you splash out the absurd cost for those discs. The only odd thing is the read speed for DVDs is still 16x, writing faster than reading is a first as far as I am aware.
In any case, this drive raises the bar a bit, doesn't raise prices much, and looks to be a pretty solid part. What can you say other than faster is better? ยต