Jailbreaking can be done by any user after they obtain a jailbreak tool. Hacking refers to someone with developer skills that is working on the development side of the community (such as the folks who create the jailbreak tools). I hope that made sense.
Jailbreaking and Hacking are one in the same. Jailbreaking is just a phrase that was coined for gaining root access to the device, but jailbreaking is a form of hacking.