@Shaz51 this is a very good question. There can often be confusion around the differences between Bipolar disorder and BPD. There can certainly be some overlap in symptoms including things such as changes in mood and for some people impulsiveness. I probably can't discuss all the differences here but people with BPD can be more likely to experience changes in mood from moment to moment rather than more distinct episodes of depressed mood or mania/hypomania. It's important to talk with your treating team though to try to better understand your diagnosis as treatments are likely to be different for the different diagnoses.
