Google can explain and so can DSM-IV but basically BPD is a personality disorder and BP is a mood disorder - if you do some reading you will see a very large difference is apparent.
Bipolar disorder is a brain disorder that causes mood swings between depression and Mania.
Borderline Personality Disorder (BPD) is a disorder of emotional regulation ability with frequent uncontrolled emotional extremes. Intense anger, fear of abandonment, low self worth and self-harm are common.
It is possible to have both bipolar and BPD.
Do a search on the National Institute of Mental Health NIMH website for more details.
I got this information from there:
"While a person with depression or bipolar disorder typically endures the same mood for weeks, a person with BPD may experience intense bouts of anger, depression, and anxiety that may last only hours, or at most a day. These may be associated with episodes of impulsive aggression, self-injury, and drug or alcohol abuse. Distortions in cognition and sense of self can lead to frequent changes in long-term goals, career plans, jobs, friendships, gender identity, and values. Sometimes people with BPD view themselves as fundamentally bad, or unworthy. They may feel unfairly misunderstood or mistreated, bored, empty, and have little idea who they are. Such symptoms are most acute when people with BPD feel isolated and lacking in social support, and may result in frantic efforts to avoid being alone."