one is for cutting, the other is for stabbing.
look at the pd's front grind - it goes from 3/16th to the edge in about a 1/2 inch, that means that metal behind the first edge, and the cutting edge angle are very wide. theres a lot of metal behind the second edge of the pd, and it has a fairly short primary grind compared to the rest of the busse line.
the ba is a more capable cutting implement to the pd (it has a full flat grin, and less metal directly behind the cutting edge)- but the pd is MUCH, MUCH stronger then the ba. the pd is for taking to hell and back when there is ABSOLUTELY no option for failure.
basically, take busse's reputation for being industructable plus its lifetime warranty, and then beef it up, thats the pd.
both are awesome - but trust me, they are totally different knives, in hand, in cutting, in grind, in a lot of respects. the handles are pretty much the same though
