It's just labels tied to books/web sites, etc. and each person defines their own program at some point.

I called myself primal at first because the first book I bought was the Primal Blueprint. The difference I perceive between primal and paleo is mostly dairy--primal, a little; paleo, only butter if anything.

I then called myself ancestral for a while as I use traditional fermented foods like water kefir, home-made yogurt and lively sauerkraut when I can find it.

Now, I've settled into "modern nutrition" as in using today's foods to achieve the best possible nutrition based on our evolution and science.

In my view, SAD is already obsolete and modern nutrition is based on everything we know about our bodies. It's not about eating only a few food types, either, it's about healing and thriving on as many quality nutrients as possible and avoiding only those foods we can't find a way to work with.

I'm a JERF 100% of the time and Paleo 80% of the time. Is it important? How good is the 20 %? if it is pure junk then yeah you need to rethink your position but if the 20% is butter, Raw Milk, some cheeses and extra heavy on the tubers, then no it seems fine to me. Judge not the best you do but the worst you do. As Homer Kelly said, re-working the garbage in garbage out quote- 'Todays garbage has to be better than yesterdays garbage.'

I sometimes refer to myself as Paleo/Primal because sometimes I eat Primal (according to Mark Sisson-- so Paleo + dairy/dark chocolate/wine/etc.), and sometimes I eat Paleo (according to Robb Wolf/Loren Cordain/etc.). The term Paleo/Primal covers both schools of ancestral eating for me.

I think most people who use the Paleo/Primal label do so simply to describe their general habits, not that they're doing something different from the two camps. Paleo and Primal are the two largest "camps" in this eating movement, or at least the two with the most exposure. So when the average person asks what I eat, I usually say "Paleo" (because most people have heard of it), and people who are more in-tune with the movement ask, I clarify Paleo/Primal to establish that I'm not firmly in Cordain's camp. In reality, I'm probably more Archevore-oriented, but that means nothing to people who don't frequent places like Paleohacks.