What Really Separates A PL From DMPL?

As all of the talk we have had on strikes, grading, toning, etc., will somebody (I'm counting on you MorganFred) give me "your" basics of Proof Like versus Deep Mirror Proof Like for Morgan dollars?

Obviously DMPL is worth more than PL with Deep Mirrors and all...BUT what makes one jump to DMPL over the a PL grade?

I just picked up a 1903-O Morgan MS64PL graded by NGC. I fell for the coin (okay, I'll admit it...I'm easy) at the coin show over the weekend and after reading David Bower's complete guide to Morgan silver dollars, I thought the story about the 1962 bank vault discovery was pretty cool. Even after reading his section on DMPL and PL and MS all from the same grade and year...(page 90)...it still can rack your brain. Considering that these 1903-O's were selling for $1,500 in 1962 dollars for Uncircuated grades...I have been searching for decent looking New Orlean strikes. New Orlean's quality control was pretty sloppy compared to other mints like San Francisco, so I was on the hunt for this historic coin in a better than 63 grade.

Well I got a 1903-O MS64PL and after checking Grey sheets, Coin Values, etc., I am happy with my buy...but I still will like to have a better understanding of PL and the line to DMPL. Also, is it possible for a MS Morgan in the same 64 grade to be worth more than the same Morgan in a 64PL grade?

Guess since I can't see the "red" of Lincolns, I better sharp up my Morgan skills.