Is ADHD really just low conscientiousness?

Conscientiousness is a fairly stable personality trait for how much care and deliberation is taken to do something "right". People who are very conscientious tend to be hardworking, neat, and meticulous, while people who are not very conscientious tend to be impulsive, scattered, and unmotivated. Similarly, people with ADHD tend to be impulsive, restless, disorganized, and have difficulty completing tasks.

I am ignorant, but it seems to me that there is an ADHD continuum that is simply the left tail of the conscientiousness continuum (normal distribution).