They will both run at the same speed as they are both CAT6.
The only difference is that one is STP (Sheilded Twisted Pair) and one is UTP (Unsheilded Twisted Pair).
All this means is that one (STP) has a foil coating arounf the wires. The only advantage of this is it stops interference.
You could only justify spending more on STP if you are running it in an area with alot of electrical activity. In most cases it's not worth the extra money.