cyclothymia vs bipolar disorder

cyclothymia and bipolar disorder both are nouns.

Word	Noun	Adjective	Verb	Adverb
cyclothymia	Yes	No	No	No
bipolar disorder	Yes	No	No	No

As nouns, bipolar disorder is a hypernym of cyclothymia; that is, bipolar disorder is a word with a broader meaning than cyclothymia:

cyclothymia: a mild bipolar disorder that persists over a long time
bipolar disorder: a mental disorder characterized by episodes of mania and depression

Other hypernyms of cyclothymia include manic-depressive psychosis, manic depression, manic depressive illness.

cyclothymia (noun)	bipolar disorder (noun)
a mild bipolar disorder that persists over a long time	a mental disorder characterized by episodes of mania and depression