Bipolar I vs. Bipolar II
People with bipolar I disorder have manic phases for at least a week. Many also have separate depression phases, too.
Those with bipolar ll have bouts of major depression, but instead of full manic episodes, they have low-grade hypomanic swings that are less intense and may last less than a week. They may seem fine, even like the “life of the party,” though family and friends notice their mood changes.