You are not alone. Everyone experiences despair and needs help getting to a brighter place, so you are not a freak or a loser. You are a tender human being who needs some loving attention paid to your thought processes right now.
In summary, it is no sin to use the terms interchangeably, though for a greater defining of an apparent hyperactive component, you may do well to describe the person as having ADHD. All ADD and ADHD persons have difficulty regulating their attention, but not all have a visible hyperactivity component.
Thoughts that are focused on the negative and on misfortune are contagious; likewise, thoughts fixed on the positive and on good fortune are contagious. As a person chooses to see things, so shall they be. Herein lies a deep and precious truth that has the power to bring joy into even the darkest of places.