Whether a person is bipolar 1 or 2 depends on the degree of mania they experience. Sometimes there's a very thin line between 1 and 2; what one pdoc calls BP1 may be BP2 to another. For instance, I was BP NOS with one pdoc, but another one, plus a therapist plus a psych nurse practitioner, diagnosed me with BP1. I believe them because I've had full-blown mania and psychosis, as well as significant depression.