They are and aren't the same. They are both forms of biofeedback. With Dr. Walkers method, it is more like traditional neurofeedback where your daughter will try and train down or train up different frequency bands depending on what her QEEG shows. It is QEEG guided because she will most likely have QEEG's done every 4 weeks to ascertain the direction of the neurofeedback. For brain injuries, I normally wouldn't recommend doing this kind of neurofeedback; however, Dr. Walker is one of the best in the country so he would be the exception.
With the LENS, it is still a form of biofeedback because the computer is reading the clients brainwaves to ascertain where the dominant frequency is. Once it ascertains this, it sends a miniscule electromagnetic wave no stronger then what a digital watch puts out into the clients brain that slightly offsets the dominant frequency and flattens the EEG, which is a very good thing. LENS practitioners are harder to find because the equipment and training is very expensive. However, as I mentioned before, this is probably the best method to rehabbing brain injuries because it requires no effort from the client, which can be a problem for brain injured clients. The LENS is also considered an advanced form of neurofeedback and the field is probably moving in this direction.
Another form of neurofeedback that has been effective for brain injuries is called Z score neurofeedback. This exclusively trains coherence and phase relationship issues, which is also a major problem with people who have post concussive syndrome. The type of injury is most likely due to diffuse axonal injury because the brain is not communicating with itself very well, and Z score training helps to train this out for better functioning.
Please keep asking more questions if you have them. If anyone else has experience with this kind of therapy, please chime in.
Also, I would suggest calling Dr. Walker and Len Ochs and ask them your questions. They are both very nice people who would be willing to talk with you. I believe you already have Dr. Walker's URL, so here is Len Ochs URL: http://www.ochslabs.com/
You may also want to talk with your neurologist or and endocrinologist about using hormone therapy to treat her. I'm not sure if they can with her young age, but it might be worth a discussion.