The Paleo diet (aka Caveman diet or Neolithic diet) isn't a diet in the way that the Atkins or South Beach diets are - there's not different versions or different "rules" that you must follow. There is only one rule - eat foods that paleolithic people would have eaten.
Unfortunately, not everyone agrees on exactly how paleolithic people ate, and that's where the problem lies. The biggest "disparity" is with saturated fat. Many older written materials still hold to the belief that it's bad for you. Also, it's only recently that the O-6 to O-3 ratios have come to the forefront, and have been linked to grass-fed vs. grain-fed meat. Cordain's book is among these "older" ones.
Some followers of Paleo-eating go so far as to not eat any fruits or veggies that would not have grown in the areas where paleolithic people lived (ie: Tomatos only grew in the "new world" and thus would have been unknown to paleolithic people.)
But basically, it's accepted that a paleo-people ate only fruits, veggies, nuts and meat. No dairy, no grains, no legumes, no sugar (although limited amounts "natural sweeteners" like honey would be fine) and no alcohol.
"The Primal Blueprint" is Mark's take on Paleo, but with a few modifications, and some non-diet stuff added in (like advise on getting sun and types of exercise.). The Primal Blueprint isn't so strict on dairy.
The eating of more fat vs. carbs (ie: fruit) is mostly a weight-loss thing. Many people following either a "generic" paleo way of eating, or following Mark's Primal Blueprint are trying to loose weight. Also, many have found that eating more fat vs. carbs keeps people satiated longer and keeps away cravings for things like donuts and french-fries. But either way is just as valid.
Nether advocates soy, or any other type of processed food.