www.cpubenchmark.net is a good source if you are curious. Though this is just other people's sample testing. Nothing to really substantiate it, so take it with a grain of salt. The Hexacore 6350 will perform slightly better in multi-threaded tasks than the 860k. Price difference is roughly $50 higher for the 6350.
CPU Mark Rating
As of 13th of May 2015 - Higher results represent better performance
AMD FX-6350 Six-Core
6,986
AMD Athlon X4 860K Quad Core
5,622
PassMark Software © 2008-2015
One of the main differences is: # of Physical Cores 2 (2 logical cores per physical) [860k] 3 (2 logical cores per physical) [6350]