I am A+ but have a vested interest in this since my wife is an O gatherer!
Hunters and explorers are reactive types generally with higher metabolisms. Gatherers have a thrifty metabolism.
Basically gatherers store fat and toxins, explorers keep them circulating in their systems and selectively react, and hunters tend to have more allergic reactions to them on a consistent basis.
O hunters can tolerate higher amounts of fat than O gatherers or explorers.
O hunters and gatherers have more red meats (and others) allowed in terms of frequency eaten than explorers (in the book at least).
O explorers have more variability in the food groups than O hunters or O gatherers.
O gatherers have black tea as a superfood, whereas O hunters and explorers have it as an avoid.