All the answers above are crap for your question.
Here is the difference. The main difference is in writing large files. The 960 EVO can write large files up to 14GB at full speed. If you write a large video files over 14 GB to the 960 pro it will fill up the whole drive (like a 100gb file) at full speed. Try making a copy of a 10GB folder on your own SATA SSD. The first few GB is fine but then it becomes slower and sllower or go systematically up and down in speed.
If your primary use is read speed, go with the 960 - if you write large files for a living can't wait another 20 seconds to offload your camera images or video, then get the 960 pro.
Here is also a quote from Ars Technica:
"Like the 950 Pro, the 960 Pro uses NAND configured to run in MLC (multi-level cell) mode, where two bits of data are stored in each memory cell, which means the drive can maintain full performance during prolonged write operations. That's opposed to, say, less capacious SLC NAND (single-level cell), which stores one bit of information per cell.."
p.s. All the crap written about drive wearing out is complete BS.