The Pro is a bit faster then the Evo. The internal controller on the PRO is different than the EVO. The PRO offer a 10 Year Warranty, meanwhile the EVO offers 5 Years.
Basically the PRO offers you the most performance. But the EVO is right after it. So, I will save some money and just get the EVO. I got one myself and its super fast!
also check this link out, has some interesting info http://www.custompcguide.net/compare-samsung-850-pro-versus-840-evo-and-840-ssd-series/