Both care greatly about what others think. Except social anxiety probably sulks and withdraws if they realize others think of them negatively. The fear of displeasing others and having probably more regard for the feelings of others, in fear they will be disliked. Narcissists on the other hand in this case will lash out and go on the offense at others they deem think negatively of them to try to either manipulate, force, or coerce them and even to hurt them if necessary, in order to "fix" them into changing their opinion, until they feel like they are being liked and being seen positively. They have very little regard of other's feelings aside from that of their own. They think in a perspective that revolves mostly around oneself and very little or even none of others.
In my view, narcissism in severe cases should actually be seen as sociopathy.
What goes up, will inevitably come back down. Whoever you have to step on when you go up, you will be at their mercy when you go down.
The truth is strictly what the ones in power perceives it to be.
Enjoy any good things, even the little and menial ones, as you will never know what impending distresses could descend upon you in a moment.