"Bipolar" refers to mood swings, which we most often associate with periods of extreme highs (manic episodes) and terrible lows (depressive episodes).

But not everyone "swings" between those two extremes. One type of bipolar sufferer has very bad depressive periods, but the "high points" top out at a more or less "normal" level, i.e. no real symptoms of mania. This type of illness is categorized as "Bipolar II".

See also the thread Will the Real Diagnosis Please Stand Up? in this forum.

Talk to your doctor as much as possible about your dx. You deserve to understand what the "label" means, that's the only way it can be beneficial to your recovery, otherwise it is just a label. Your doctor owes it to you to answer your questions about it until you understand