I can see the differentiation being necessary/useful for treatment formulation, monitoring of treatment response, and so on, but why on earth would an insurance company need to know the ins and outs of a duck's behind when it comes to what you're treating a patient for? Why is it any of their business in the first place? You're the Psychiatrist, you've deemed it necessary that this patient requires treatment, you denote what that treatment should be owing to the fact that you're the one who actually went to medical school, so unless the insurance companies have their own Doctors to independently examine the patient themselves and decide the patient does not in fact require treatment, then the insurance companies should just mind their own business and let you guys get on with your jobs (which I imagine would be a lot easier if you didn't have umpteen dozen different billing codes to deal with).