the 2 versions are exactly the same however i do believe there are some import/export limitations with the student version. I don't think the student version can do stl or vrml.
what is your primary concern? if you are a student and trying to learn the software, get the student version. if you have a 3d printer or similar that you need an STL for, use the EDU version that you have at your school.
if you're a working professional, you don't have much choice but to get the professional version. otherwise you're outside the EULA.
Thanks, Mr. Conway. The EDU version at my school works well as '3D Print' is my primary concern.