No it is not true. Your friend is wrong and you are right!
Sociopaths is technically having Anti social personality disorder. One of the main characteristics of sociopaths is a disregard for the rights of others. Some symptoms include physical aggression and the inability to hold down a steady job. However, they may be extremely charming and master manipulators, but eventually their true selfish intentions show and it may be hard to sustain relationships they also show a lack of regret for their bad actions. A major personality behavior trait is the violation of the rights of others. This can appear as a disregard for the physical or well-being of another. But, the main characteristic that trumps all others is lack of empathy or in other words not feeling sorry for the bad things that you have done. And of course another big symptom is being extremely narcissistic and only worrying about yourself. But, it most definitely is not the same thing as Narcissistic personality disorder.
Narcissistic personality disorder is when an individual is described as being excessively preoccupied with themselves. They might believe things like they are extremely smart, beautiful, powerful, ect. They require excessive admiration and usually feel entitled. They are also extremely envious people so they might get jealous of others and their success very easily. They also show a lack of empathy, but it is not nearly as extreme as those with anti social personality disorder.
However, I can see why your friend might think they mean the same thing...generally Anti Social Personality disorder is mostly diagnosed in men, but when women exhibit these symptoms they are diagnosed as having Narcissistic Personality Disorder instead. So there is quite a lot of controversy there and there still needs to be much more research done on the topic. Now, with that being said the Diagnostics and Statistical Manual of Mental Disorders (DSM) gets updated every ten years or so and the new DSM which comes out in May 2013 will not include many of the personality disorders that are include in the current DSM. We can't be sure of which ones they will eliminate until the edition gets published, but they are pretty sure that Narcissistic Personality Disorder is one of the ones that will get tossed out.
Sorry if it was long, but Anti Social Personality Disorder is my favorite disorder to learn about lol so I hope this helps. And sorry, sound like with even all your good info that you told your friend you still will not be able to convince her lol