Okay, I haven't broken down the full list of features to compare, but let's look at the stuff I know that I can compare.
First off, Daz is only selling it to Platinum Club Members and at reduced pricing, which in itself is a pretty cheap way to get folks to join that, and a poor substitute for Smith Micro's Pre-order pricing.
So, Here's the breakdown of prices (pre-order price in parenthesis):
D|S Advanced: Upgrade $109.95 ($65.42) Full: $229.95 ($136.82)
D|S Pro: Upgrade $334.95 ($187.57) Full: $429.95 ($240.77)
Poser 9: Upgrade $129.99 ($79.99) Full: $239.99 ($149.99)
Poser Pro 2012: Upgrade $199.99 ($149.99) Full: $499.99 ($249.99)
As we can see, the prices are almost exactly in line, almost like DAZ copied Smith Micro's Pricing and then dropped it a little to make themselves look more attractive. The big difference is the Poser Pro Upgrade pricing, which just blows the D|A Pro upgrade pricing out of the water. Other then that, all those non .99 digits are just there to confuse us and make it look great, it's a marketing tactic I am familiar with, being in retail.
Then there's another difference, one Daz has done it's best to hide. What is that? Hidden by default, in the description of D|S 4 description is one line that will make certain users rage.
NOTE: DAZ Studio 4 Advanced is not stable on Mac OSX Lion.
Would love to see a technical breakdown of the differences by one of our Ambassadors.