There's been much discussion of narcissists and sociopaths in some of the circles I run in recently. This article --
http://www.huffingtonpost.com/2013/05/13/sociopath-signs-is-your-e_n_3181512.html -- describes the difference between them succinctly and well:
So what's the difference between the two? A narcissist needs to be validated by others, and a sociopath doesn't. A sociopath will exploit others because he finds it amusing, while a narcissist only exploits those he believes is a threat. If you are dealing with a sociopath, stop playing his games. He enjoys pushing your buttons just for the fun of watching you squirm. If you are dealing with a narcissist, don't feed his ego and avoid falling prey to his traps.
More relatively recent articles:
http://live.huffingtonpost.com/r/segment/learning-to-love-the-sociopath/51c1ea6a02a7602946000312http://www.npr.org/2013/06/19/193099258/inside-the-mind-of-a-sociopath?sc=tw&cc=sharemore from the author of that book:
http://www.sociopathworld.com/ I have to say, the articles do tend to make me go "hmmmm...."