What is the difference between the two processors
The best answer
the question has already been answered well - nevertheless:
- k versions of Intel processors feature an open or unlocked multiplier and can thus be simpler, better and higher overclocking. A processor without "k" suffix you can also overclock when the multiplier was not completely blocked, but not nearly as easy and good, it is not usually recommended.
- If you want to overclock a good board with matching pedestal recommends. Best overclocking the boards are with Z or X chipset, which are supporting the base and compatible.
If you are faced with the decision, I'd way rather than the i7 without "k" prefer a Xeon E3-1231v3 - is cheap and has hardly any disadvantages compared to a "k-loose" i7 ;-). However, the Xeon is a processor whose Multi been banned here so you could not overclock the i7 probably.
k = free multiplier = easy to overclock!
requires appropriate motherboard.