covert narcissism and petulant borderline personality disorder similarity

the correlation of these two has been on my mind for a while
i just cant see how they could be distinguished
probably because i lack research here
anyone here who knows both of these well enough?
i'd like to hear your understanding of these personalities if you have had an experience with both! or learnt about both well enough to make clear distinction

i think they overlapp and the lines are very blurred :/ maybe one exhibits its self in form of traits while the other is most prominent? but whenever i read about the traits a person exhibits, with any of these disorders i i get confused because that sounds like the exact same person :( have u been exposed to both of them to make a distinction?