They are one in the same; diagnostic as well as therapeutic. But just remember if they don't work, the docs will have to look further. I had them in my scalp at first; greater and lesser occipital nerves. They did help for awhile but not long lasting. But again, my issues were from the cervical spine itself. And you don't get these all the time as say you would in taking meds. The docs really don't like to give a lot of injections as in managing pain. I just mean you can't keep going back and having them done over and over and over again. Eventually, they will find a different procedure. For instance...I will be getting a C2/C3 facet injection tomorrow. This will be my second one in 8 months. After that and if this gives me good pain control, the doc will do a radiofrequency ablation. But everyone is different with different reasons for ON. I know of some who have opted for a stimulator. So, I think it all just depends on what is going on. And I want to add I feel for anyone that has this going on. It has to be the absolute worst pain I have ever had in my life. I have spinal issues galore but nothing has topped the ON...not yet anyway. I wish you all the best of luck and success in getting some relief from it.