Some people do a good job of making it known that they are one or the other. I used to have a coworker who was very brusque, bordering on rude, not because he was actually an asshole, but because he just didn't really pick up on a lot of social cues, was a little socially awkward, and it would not have surprised me at all to learn he had mild, un-diagnosed autism. But he never got in trouble for it, because even the people who didn't particularly like him personally, knew that that was just his personality, and he meant absolutely nothing bad by it. He enjoyed his job, enjoyed his coworkers, but just did not have the time (or ability?) to worry about social graces.