ADHD Levels

Are there different levels to ADHD?  My husband (although undiagnosed) has ADHD -- I'm positive about that based on the symptoms but he doesn't exhibit as much severity with it in some areas as other people do.  Yet, he is a poster child for it in other ways.   He does household chores -- many, in fact.   But he is so distracted when driving, it scares me.  AND -- he rides a Harley Davidson sometimes too.  He kept the same job for 20 years, then moved to another area and has had 7 jobs in the last 2 years.  He's spontaneous and fun but can become angry over the most trivial things.  Yet, other major anger triggers don't bother him.   Does everyone who is ADHD NEED to be on medication?  I'm new to this and want to help him and keep our marriage from disaster like I keep reading other's have fallen into.