NO , they will both overclock that cpu to the same speed , there is no advantage with overclocking. The extra $50 is for some added features like a couple more sata ports or a couple more usb ports. In this case the Delux model has WIFI added plus there are two lan ports instead of one.
"Looking at the P9X79 Pro and Deluxe, one could argue that there's no real difference between the two boards. The biggest change is the 16+2+2+2 VRM setup on the Deluxe over the 8+2+2+2 setup on the Pro. The higher amount of power phases means that overclocking ability should be a little better on the Deluxe version."
It means that the delux board has a better power phase design setup and that when going for the higher end of the overclocking on the board the Delux model will be better at providing the voltages needed. So if your intention is to try to overclock the cpu that you have to the highest it will go then the Delux board will get you there and the Pro model may not.
From yourr post it didn't sound like you know very much about overclocking and to get to the clocks at the higher end of the overclock you have to have a lot of experience because it involves makeing numerous adjustments to the bios settings on the cpu voltages.
The thing with overclocking is that you have to know how to do it and know what it takes to do an overclock and the best thing is experience. The only way to gain experience is to do it and also read up on it and ask questions on forums like this one. When first starting an overclock the thing that you do and it's the easiest part is to change the multiplier on the cpu in the MB bois. That changing of the multiplier will then change the speed of the cpu and you want to do it slowly and test the stability of Windows at each point of change. So this becomes a tedious time consuming process but it's what you have to do because you just can't go into the bios and say that you want to have 4.5ghz so I'm going to change the multiplier to 42 or 43 and think it's just going to be it and your done. The process takes time and you want to make sure that your learning from it so you can advance and get better at it. At some point Windows will become unstable and at that point you have to chose to stop and back off 10% to get a stable Windows or to add voltage to continue. By adding voltage that will in turn make the cpu and then Windows stable nd you start over with the multiplier untill Windows again becomes unstable and again you add voltage.
Now this explanation is the condensed version since I don't want to take up the whole page with insrtuction but that is basicly how an overclock is done and the hard part is the voltage because in the bios you are working with tenths and hundreds of a point of voltage to be applied at a time to the cpu so that's why it's tedious and time consuming and you have to have a lot of patience to get to a stable high overclock , but in the end it's worth it since your computer is now running at a higher rate of speed thanks to the overclock.
Just starting out I would not do any voltage adjustment untill your comfortable with what has to be done in the process , so an oveclock of 4.2 ghz would be good for the novice person. That could be accomplished by just adjusting the cpu multiplier.