A:Answer Assuming you're talking about the a7rII, the a9 has a much faster burst rate (20fps vs 5fps), better autofocus system, and faster operation overall. Plus a larger battery, dual card slots, and ergonomic improvements like the joystick and shooting and af mode dials. The a7rII has more resolution, but is a sluggish body. I own both the a7rII and a9...they both have their purposes. The a9 is better suited for sports/action/events, and the a7rII is better suited for landscapes and posed portraiture.