It really depends on what you're trying to do. The Student license, if you have access to the license through your university, is a LOT cheaper and as far as I can tell, essentially feature-complete. The Academic license gives you some more options about where you can have the system installed (for instance, on up to 4 PCs), but it's something like 5 times the price. The one major difference I have found is that the Student license does not have access to the same set of add-on packages; specifically, you cannot buy the Matlab compiler package for the Student version. This might or might not affect you whatsoever.
Unless you know very specifically you want this particular package, I would say there's essentially no disadvantage to buying the Student version, and you save a lot of money in the process. You can always give the Mathworks sales team a call to discuss your needs; they're very helpful.