I can understand that, but if Nisargadatta claims that all changes in consciousness are based in the belief that "I am the body" then there is a real difference because the Buddha teaches name and form, not just form (ie five skhanda, not one) as being the objects onto/by which the self is imputed.
I'm not sure it's so much "Nisargadatta claims," as "Nisargadatta responded to a particular question with..." Sort of like Buddha claimed some things in the First Turning, others (that contradicted the first) in the Second Turning, and as Sogyal Rinpoche says, even Buddha's tongue was tied when trying to describe Mahamudra.
Actually the very next answer Nisargadatta gives is an example of the "provisional teaching" style:
Q: The other day you told us that there is no such thing as karma. Yet we see that everything has a cause and the sum total of all the causes may be called karma.
M: As long as you believe yourself to be a body, you will ascribe causes to everything. I do not say things have no causes. Each thing has innumerable causes. It is as it is, because the world is as it is. Every cause in its ramifications covers the universe.
When you realise that you are absolutely free to be what you consent to be, that you are what you appear to be because of ignorance or indifference, you are free to revolt and change. You allow yourself to be what you are not. You are looking for the causes of being what you are not! It is a futile search. There are no causes, but your ignorance of your real being, which is perfect and beyond all causation.
Actually, he did
say things have no causes -- in response to another questioner, in another context. And as for the words "your real being" above, lest anyone take it to mean him advocating a "real self," the rest of his words make clear that this too is a provisional teaching. "Your real being" ends up sounding a whole lot like Buddha-nature.
Anyway, I've said my piece about the relationship between the teachings. This post is primarily to help clear up a "but the Advaitins claim that..." idea.