What's the difference between bipolar I vs II disorder?

Severity. In a nutshell, bipolar i is more severe than bipolar ii. Bpi experiences full-blown mania with generally some loss of contact with reality, mood swings are severe and judgment at times is impaired. Bpii tend to become only hypomanic, which can still be problematic, but not as severe as mania.
Mania vs hypo mania. Bipolar 1 is characterized by mania with or without depression. Bipolar 2 is hypo mania with or without depression. Hypo mania includes increased self esteem and productivity, and usually decreased need for sleep. Mania includes psychosis and/or major social consequences and frequently requires hospitalization. Both are treated with a. Mood stabilizer.
Degree of mania. Bipolar i is characterized by manic symptoms that can include increased energy and a decreased need for sleep, racing thought, rapid speech, marked impulsivity, grandiosity, delusions, etc. These individuals are usually very impaired and require hospitalization. Bipolar ii is more of heightened creativity and productivity, followed by a crash into depression.