The 850E lacks a handful of high end feature as compared to the 900E that may or may not be important to you. Specifically, the 850E lacks something called 'local dimming' which create deeper blacks. Deeper blacks create greater contrast and a every so slightly brighter picture. Having said that, the 4500:1 contrast ratio on the 850E should be more than sufficient for most viewers. If you watch a lot of true 4K content or have 4K gaming equipment, you might feel the difference is worth the extra money.