The new 850 Pro and 850 EVO SSDs double the maximum capacity of the current SSDs.
Like their predecessors, the new 850 SSD Pro and EVO drives remain in the same 7mm, 2.5-in.
The storage capacities include 120GB, 250GB, 500GB, 1TB and 2TB.

Both the SSD models come native with full AES 256-bit full disk encryption capability, like the previous SSDs.
The biggest difference on paper is the specified durability and the length of the warranty.
Samsung 850 Pro was reviewed by Computerworld last year and it was found to be quick and cheap.

source: www.techworm.net