Arrogance or Self-confidence?
I have come across both types of people in my life and I will admit I have mixed up the 2 at times when I was younger.
It can be difficult to tell them apart as they have many cross over points and until you get to know someone the lines can be even more blurred.

What is confidence?
Confidence comes from belief in one’s abilities. A confident person is one who knows he has certain areas of strength and weakness. A confident person feels confident in themselves. Though they are also human beings, and they too feel good when told they are better at some things than others, and they too find gratification with validation, but they are not dependent on this. It's a boost rather than a necessity. They try to be of use with their talent, and they succeed at the task at hand because of their ability.
What is arrogance?
Arrogance is an exaggerated version of confidence. Arrogant people can be seen at all places. They are those who think less of others or someone in their surroundings. These are people who can be seen correcting the flaws of others or showing them the right way of doing things.
An arrogant person is more interested in being proven right than being happy. In a discussion, they go all out to prove they are right by dismissing other’s arguments. To be proven right is the most important objective for such people, even if this comes at the cost of reducing other’s status or making them feel lesser.
Unlike a confident person, an arrogant person is dependent on validation. Thus, the difference between a confident and an arrogant person is not on abilities, but on having calm control over themselves. An arrogant person tries to belittle others by displaying his abilities while a confident person displays his abilities only in case of genuine need.
Arrogance stems from a sense of insecurity, and a person is arrogant to compensate for areas of weakness that cause distress for such a person. Arrogance breeds superiority.
Of course, anyone can cross over this thin line including ourselves and certainly give the impression that we are showing signs of arrogance when we think we are just being confident.
What is the Difference Between Confidence and Arrogance?
Arrogance breeds superiority, while confidence makes others comfortable.
Arrogance may be a way to suppress feelings of insecurity for other areas of weakness.
A confident person takes into his stride both strengths and weaknesses.
Arrogance feels good by making others feel lesser.
Confidence is an attribute liked by others.