Good question. It’s always the degree of those traits.

For example, narcissists struggle to empathize with the feelings and needs of others. To some degree all humans struggle with that: we can never know exactly what someone’s feelings are. But if someone began crying in front of you because they said that you hurt them, you’d feel bad. A narcissist may not feel bad and may actually attack you (e.g. gaslighting). Seeing someone cry in front of them may elicit a defensive response instead of an empathic one.