What's the difference between inattention in ADHD (short attention span) and spacing out?

Quite similar. The attentional problems with adhd are of two broad types: inattention and distractiibility. Inattention is trouble staying focused on a topic, even with the best of intentions, and "spacing out" can be a manifestation of that. Distractibility has to do with being unable to a new element in the environment when one needs to stay focused on something else, jumping from one activity to another.

Related Questions

I have problems with zoning out. Short attention span. Easily distracted. Sometimes getting up muptiple during a small period of time helps me. Focus.

Practice. All of us get distracted easily. Focusing takes practice, and it's not easy for anyone no matter what they say. Try focusing on a long term goal and then keeping disciplined in taking the steps to reach that goal. With each successive step, your confidence will grow stronger and your focus will also. Give it a try and see if that gives you some perspective on it. Read more...