What is the difference between the "relationship" field and "profession" field in an individual relationship within an organizational constituent?  Listing "employee" under "relationship" isn't helpful because it's obvious that they are an employee.  Does anyone use different terms that help link individual relationships to the organization?

The relationship might be something along the lines of employee as you suggested (which may not always be the case - an individual relationship could be a Board Member or former employee or Legal Council) Profession could be actually what the employee does such Executive, Management, Finance, Worker Bee, etc. This way you're not confuising Position/Titles with Professions and relationships which I have seen some confusing crossover with over the years.