Re: It's just mathematical equivalency
If it is a mathematical equivalency then both descriptions are equally valid but there may be some circumstances in which it easier to calculate something with one formulation than with the other. This contrasts with things like the difference between relativity and newtonian physics where the two theories predict different things.
I'd imagine that for most things it would be easier to calculate things using the theory describing 3 dimensional space. The laws of motion etc on the holographic surface would probably be a lot more complicated. If this mathematical equivalence does exist then that is a new mystery. Why should a description of the universe have to support such an equivalence ?