Samsung may have introduced the 850 EVO line as a “cut-down” version of their 850 PRO line but these two are not really that different something which is a very good thing for consumers. For example both make use of 32-layer 3D V-NAND flash modules (V stands for vertical) and so both also share the same endurance rating of 75TBW for the 120/250GB models and of 150TBW for the 500GB/1TB models (this translates to 40GB writes for the first two and 80GB writes for the last on the drive per day for a period of roughly 5 years). The 840 EVO line also features the same TurboWrite technology (a small amount of SLC NAND flash is used to accelerate write performance), DevSleep (power saving feature), TCG Opal 2.0 & IEEE-1667 (AES 256bit hardware encryption) and RAPID v2.1 (uses up to 4GB of your system memory to boost read/write performance). For the new 850 EVO line Samsung has made use of two brand new NAND flash controllers, an 2-core MGX one for the 120/250/500GB models and an 3-core MEX one for the 1TB model. Unfortunately we have no detailed specifications for the MGX controller (or for the MEX one) but we do know that Samsung gives it an MTBF (Mean Time between Failures) of 1.5 million hours.

Link