The DSM criteria is not God. If you don't make the cut, that doesn't automatically mean you're not autistic.
And the specific difference between them can't be stated. I don't know if the people born with autistic traits who never met the criteria are autistic or not. I don't know if someone is autistic. Typically only the people themselves know. Of course, anyone can decide they are no longer autistic. That's fine. But then it'd be quite odd to frequent an Autism forum.
ASD is just a label to describe people with a certain set of symptoms. The DSM, at least in the US, defines who is and who isn't autistic. If you meet the criteria, you're autistic. If you don't, you're not. It's that simple.
Of course, it's debatable how it should be defined. I personally would like to see symptoms split between genetic and psychological so that those born with autistic traits can be diagnosed with autism and have those with additional symptoms diagnosed with other co-morbid conditions. I think there's a good chance it will end up that way with autism being diagnosed as a neurological condition affecting 1 in 10 people with new co-morbid conditions being diagnosed in a future version of the DSM for those with additional symptoms.