Student files are not incompatible, but as soon as a student licensed copy touches a part or assembly, it becomes "tainted" (such that it says "student edition" in the corner or something). I worked at a university-based company where we had a bunch of student licenses and a couple pro licenses, and we had to be very careful about separating the files and making sure that the student edition never touched our professional files.
And the Student version is only available to people with a valid current student ID, and saves files in a format that is intentionally incompatible with the normal version?