I used to wonder the difference between these two. It seems to me that both speak authoritatively about a given subject. Both attempt educate. Each might be confused for the other, but there are differences. An expert is hungry for knowledge. He wants to know all there is to know about a subject. As such, he listens to input from others on a subject to see if there's something new or undiscovered about a suject. Experts can seem humble because they can be slow to chime in, preferring to listen to a problem before offering a solution. An expert will take the time to say why something can't be done. He'll also be willing to acknowledge when he doesn't know something. None of these are true of the "know-it-all". He's quick to offer advice, slow to listen. Instead of learning from an expert, he'll be the one to point out any of the expert's short-comings. Case in point. I was in a uniform store. A woman, in training to be a nurse's aide, walked in to buy her first set of scrubs. Despite being surrounded by people who work with them everyday, she kept disagreeing about the nature of the fabric, the cut of the clothing, etc. The people who clearly knew better about the suject, were forced to be quiet or risk a confrontation with someone assured of her wrong opinions. In the end, no one learned anything. That's the difference. With an expert, you'll learn something and feel more intelligent. With a know-it-all you'll learn nothing and feel stupid. Paul