To start this discussion I would define the difference between the two as
- A professional association has future members complete their theory training before attempting the practical training. They also accept students that wish to attend classes and work at the same time period.
The student can not sign off on his work until fully competent as judged by those already having professional status.
- The trade association has future members combine the field and theory training at the same time.
During the training period they perform work and take responsibility for it. The apprentice process.
Other associations call for fee paid inspection as part of the requirement to obtain certification.