Cyclothymic disorder and Bipolar disorder are very similar in several ways.
However, a list of characteristics differentiate them from each other:
Cyclothymic disorder:
The people suffering from cyclothymia have periods of depression, hypomania or mania that last from 1-3 months.
They also have periods in which the symptoms are not present. It does not have the regular patterns of the mood changes that bipolar disorder has.
Bipolar Disorder:
They have regular patterns of mood changes. They have longer duration of symptoms.
The mood changes usually last for more than two weeks. These mood swings are also not limited to depression or mania. In between these mood swings, they can also remain stable.
For an accurate diagnosis, you must consult a psychiatrist who can tell the difference between the two disorders.
There is not much of a difference in the treatment of the two disorders.