1 It's confidence.
2 People are quick to label others arrogant when a significant amount of pride for ones own accomplishment is demonstrated by the receiving party. This sentiment usually comes from people that are incompetent.
3 Identifying them is as simple as looking at their non-existent accomplishments in the relevant subject matter. The irony is that most people label others arrogant in the midst of their own arrogance. Arrogance is demonstrating pride without accomplishments.
4 Confident people demonstrate competence through accomplishments as confidence is a byproduct of accomplishments; which is a byproduct of competence.
