Lolno. You can overclock an i7 if it has the "k" suffix in the end. Overclocking is when you increase the voltages the CPU is using, to make it run faster, which also means you'll need a better cooling system. Hyperthreading will allow your computer to also multi-task with applications, making the system more flexible. Generally speaking though, extreme is better, but if you're only going to play minecraft, then you can save a lot of money just by getting an i7 4770k / i5 4670k. Never will you need an i7 extreme for minecraft.

Oh

i7 Extream has an unlocked multiplier. Overclocking is where it increase the speed of your cpu. Hyperthreading is simulating more cores then the cpu has.