I think the biggest difference lies in what the individuals bring to the work. A professional, working in a major orchestra, brings a wealth of experience. The professional has a different set of needs than a student has. For example, members of the Philadelphia Orchestra have performed Beethoven's 3 rd Symphony countless times in countless ways. What they expect is a real definition of approach.
Students bring an entirely different set of needs to the process.
I think their biggest need is information. Working with professional musicians with a mastery of instrument and repertoire is exciting. But it's also exciting to work with students who approach the music with questions and a fresh eye. It keeps it fresh for me and reminds me how much I love it. I don't expect less from students.