If a visit to each school is not possible at this point, encourage him to make a list of criteria that he is looking for in a program. Then, list the pros and cons of each program as they meet those criteria.
Both schools are in cities... but NYC is a very different city than Boston. Does he have a preference for one or another?
Both schools offer conservatory level training... but NYU is part of a larger university with all of those resources, has more academic requirements, offers the ability to double major, and offers the possibility of exploring another studio for advanced training. BOCO is a much smaller institution and all student studying there are in the arts. There are fewer academic requirements.
Similarities and differences will go on and on... BUT, it is how they stack up against your son's criteria that will help him make the final decision.
Both are strong programs, so it really is a matter of what each has to offer in relationship to what he is looking for.
Years ago I was deciding between Syracuse, NYU, Ithaca, and Emerson.... never even applied to BOCO because my NH Boarding HS had been super small, and I wanted a larger more diverse college environment... I had visited each, but could not go back for second visits after being admitted. I was able to make an educated decision I was VERY HAPPY with based upon weighing the pros and cons against my own personal criteria. With things like facebook and email, I am sure that he can communicate with current students in each of the programs to help him get a sense of the student culture at each school.
Great problem to have... deciding between two great schools.
All the best!