You don't have to use both, one or the other will root the phone and make it NAND unlocked so you can flash ROMs and Kernels.
I don't know if you already have experience with the step-by-step method posted as a sticky, but you should give it a read through so that if on the off chance you get stuck with Unrevoked, you can pick up or start troubleshooting using the step-by-step method.