One common question is "What the difference between paleo, primal, and Atkins?" So I made this chart. But in some ways it's very hard because as the science becomes stronger, there has been a strong convergence between the three. For example, many Atkins devotees have realized that they just don't do well on low-carb Frankenfoods. And Cordain has come around with regards to saturated fats.
I put markers on for the most popular "gurus." Kurt Harris at PaNu basically espouses a unprocessed carb-restricted version of paleo which could pass for Atkins. Mark Sisson advocates a fairly laissez-faire approach with the goal basically to avoid the worst foods that aren't on this diagram anywhere. Robb Wolf recommends different things for different goals as I wrote in my review. Loren Cordain is mostly about specific foods and is still down on dairy and nightshades. I guess now that he's writing more and more about how bad those are, they might end up next to dairy in this diagram.
Where am I? I guess the closest to what I do it Sisson + Wolf. I'm moderate carb and do eat some dairy sometimes. Where are you? Quibbles? Questions?