Fucker is a person, but пиздец never is. Apart from being an expletive it is also an abstract noun with meaning ranging from bad luck to unpleasant fate, future or present: "пиздец вам пришёл" (literally "your pizdets has come" or even "pizdets came to you") would mean something like "you're fucked". Often, you don't even have to specify the recipient of the pizdets, which has to be deduced from context: "ну, всё, пиздец" usually means "that's it, we're fucked" although "we" isn't mentioned. It appears as if it were an expletive here, but it really is a meaningful sentence on its own (cf. screamimng "punk'd!" or typing "p0wned!" to mean "you have been punked/owned!")
Surely related to Russian pizdyets, always pronounced with a note of exasperation! I sense that this is quite different from the (bitter? I'm talking society by the way, not flavour) connotation of cunt in the west. A pizdyets often came out when someone dropped a glass on their foot, for example, almost as part of a laugh at their own stupidity.