I've worked in the mental health field + studied the DSM.....
BP1= You've had at least one manic episode before or mixed mania, where you meet full criteria for both mania and depression concurrently. Manic symptoms last for at least a week straight to be considered an episode, unless the person ends up hospitalized...then a full week wouldn't be needed for diagnosis. Psychosis is not uncommon during the manias/mixed-manias, although this is not a requirement for BP1 and usually is secondary to mania.

BP2= You've experienced Hypomania (lower level mania), but never full-blown manic episodes. Mixed symptoms would not meet full criteria for mania either. Depressive episodes tend to be predominant.

The DSM-5 lists full criteria for those who are curious further about distinguishing the two. Sometimes the criteria is tricky and two pdocs may not agree on it being BP1 or 2 since some of it is subjective. So it can be confusing.