The main difference between one and the other is a matter of self-perception.
Narcissists have an exaggerated perception of themselves
The main difference between someone who is narcissistic and someone who has good self-esteem is their self-image. That is to say, the former gives himself exaggerated and truly distorted importance; the latter enjoys a much more interior and less inflated self-satisfaction, with more reasoned foundations.
A narcissist seeks well-being and security by means of an exaggerated image, which in reality is a distorted self-perception. That is to say, narcissism actually reveals an interior emptiness in which an insecure person is hiding.
By way of contrast, a person with good self-esteem bases his well-being on satisfactory relationships. In other words, he doesn’t give his image more importance than it really has. Since he has self-confidence, he doesn’t need to exaggerate or over-emphasize his triumphs when dealing with other people; he simply enjoys celebrating them.
Assertiveness vs. a need for attention
A person with high self-esteem is assertive. He knows how to listen, how to pay attention, and how to choose the right moment to speak, and he knows what he is talking about, always making a valuable contribution with his words. That is to say, he has emotional intelligence, and the patience that comes from knowing that he will be able to express his opinion when his turn arrives.
A narcissist, on the contrary, given his inordinate cult of his own image, needs attention. That is to say, he will always try to be in the limelight. Consequently, he will try to become the “life of the party” and will make sure everyone knows he’s there. He needs other people to be admiring him constantly.
Arrogance instead of compassion
While narcissists never show compassion for anyone, except perhaps for themselves, people who really have healthy self-esteem are aware of the value of the beautiful challenge of helping other people.
Narcissists, in their arrogance, are generally aggressive and envious, and feel a need to dominate others in order to feel good about themselves. Rarely will they accept criticism or learn from their mistakes, because they have great difficulty in perceiving—and above all, accepting—their weaknesses and failures.
A narcissist and someone with healthy self-esteem could, at first, seem similar. However, as time passes, and the two personality types develop, we can see how the similarity between narcissism and self-esteem vanishes like a mirage. Empathy is the greatest quality that shows the difference between these two kinds of personality. People with healthy self-esteem can always grow in their capacity for empathy towards others, fostering sentiments of collaboration and love for others. A narcissist, as such, cannot develop this quality.