Depression occurs in almost all people with manic depression, but not necessarily. With manic depression, manic episodes occur. A manic episode may be full blown or may be less intense.
Mania is the term used for the full blown episode.
Mania is the most severe of the two states. The symptoms described apply to both states. It is usual for an episode of depression to follow an episode of mania or hypomania. Sometimes a period of normal functioning will happen between episodes. Feelings of boundless energy.