Here’s a table from Wikipedia that should help:
Characteristic….........Healthy Narcissism…............Destructive Narcissism
Self-confidence….........High outward self-confidence….An unrealistic sense of superiority ..................................in line with reality….................(“Grandiose”)
Desire for power,..........May enjoy power…..................Pursues power at all costs, ..................................wealth and admiration…...........lacks normal inhibitions in its
................................................................................pursuit
Relationships…...........Real concern for others and…...Concerns limited to expressing
..................................their ideas; does not exploit…...socially appropriate response
..................................or devalue others…...................when convenient; devalues and
................................................................................exploits others without remorse
.
Ability to follow…........ Has values; follows through…... Lacks values; easily bored; a consistent path…........on plans…...............................often changes course
Foundation…...............Healthy childhood with support ..Traumatic childhood undercutting
..................................for self-esteem and appropriate…true sense of self-esteem and/or
..................................limits on behaviour towards…..... learning that he/she doesn’t need
..................................others…....................................to be considerate of others