The postcyberpunk genre arose as kind of a backlash-reaction to the cyberpunk genre. Somewhere along the line, it seems like people got tired of the stylish grittiness and dark portents running rampant in the cyberpunk genre, and there are many, many people out there who, when confronted with stories that do not have a very happy feel to them, say the same thing when rejecting such tales: "It's too dark!" While that refrain has become something of a running gag in my household, I understand that people have differences of opinion about what constitutes enjoyable fiction, and that a more escapism-oriented mindset for a reader can find itself dissatisfied with dark, dystopian futures.
Typical descriptions of postcyberpunk, when distilled into an elevator pitch, come with some common characteristics:
The stories and settings tend to be bright and hopeful.
The protagonists tend to be "mainstream", and the antagonists on society's fringes (criminals, basically).
The authorities (corporations and governments) tend to be good, stabilizing forces.
All of these characteristics run directly counter to tendencies in cyberpunk, where:
The stories tend to be dark, grim, and laden with despair.
The protagonists tend to be those living on the fringes, semi-anonymous outsiders who end up fighting against an oppressive mainstream -- criminals, often because criminal acts are the right things to do, while more "mainstream" characters are either antagonists or "sheep" living stultifying lives as tools of corrupt plutocrats.
The authorities (corporations and governments) tend to be bad, oppressive forces.
This does not really bring home the significance of these differences, though. There are those who regard cyberpunk as passé and tiresome, so thirty years ago, and postcyberpunk as a somehow more "mature" genre, but I find this manner of differentiation superficial, to say the least. Both genres still have important contributions to offer to our literary culture. Ignore the most style-over-substance works in both genres, focus on the more insightful examples of each, and consider what I have come to realize about these genres.
It turns out postcyberpunk and cyberpunk are basically the same world. The difference between them is one of perspective, and not setting. Postcyberpunk stories are typically presented from the perspective of upper middle class white-collar workers, and cyberpunk stories from the perspective of those forced to make money illegally on the fringe of society doing dangerous things. The protagonists of each genre are often the antagonists of the other.
Perhaps more interesting about all this is the fact that we now live in a world that neatly matches the tropes, themes, and attitudes of both cyberpunk and postcyberpunk. The world in which we actually live is almost exactly like a world that -- depending on who steps into the role of main character -- would be a great setting for both. All that we're missing are the more obvious superficial trappings of each, including things like strength and speed enhancing cybernetic technology and biotech of both, painfully obvious and tragically hip in cyberpunk while remaining subtle and largely invisible in the other, along with the highly advanced artificial intelligences lurking behind the scenes of both. It's not too difficult to imagine at least nascent variants of both in the world today, especially because we already have them in the form of things like IBM's Watson, subcutaneous RFID tags, artificial organs, and so on.
Both genres fit the world in which we live today equally well. Ponder these example characters, people who (for all meaningful intents and purposes) exist right now, in the real world:
John is a Microsoft Exchange administrator with a two-story, five bedroom house in the suburbs. His wife is a real estate agent. They own a huge SUV, and they have 2.5 kids, a dog, a cat, a white picket fence, and all the latest pop-gadgets -- iPhone, iPad, Microsoft Surface tablet, IoT refrigerator, and so on. John voted for Clinton, but he had to hold his nose to do it. He heard once that Bitcoin is for criminals and Linux is for hackers. He may have these beliefs strengthened by an unfortunate virtual encounter with ransomware, operated over IRC servers run on Linux, that demands payment in Bitcoin.
Jane is an open source developer working for the Tor project with a studio apartment in the inner city and a goth/industrial nightclub DJ for a girlfriend. She has serious problems with authority, wears a lot of black, sneers when she calls people with children "breeders", and rides a bicycle with an electric motor attached to it. She uses a Novena open hardware laptop running OpenBSD as her operating system, and has a bunch of DIY automation stuff in her life like an Arduino plant watering device and a hand-assembled digital password manager device she programmed herself. She secretly works to undermine the corrupt government, thinks Clinton and Trump are both evil incarnate, and uses Bitcoin for most of her financial transactions other than rent and food.
William Gibson once said "The future is already here. It's just not very evenly distributed, yet." That wasn't true only in the abstract; it is largely true in the specific cases of the cyberpunk and postcyberpunk genres, too.
This is the world in which we live. Neither cyberpunk nor postcyberpunk is the future any longer; it is, effectively, the present. "Cyberwars" between world superpowers, "hackers" spoiling elections by the expendient of sharing truths pilfered from the corrupt politicians' own computers, people getting locked in (or out of) their own hotel rooms by malware, and shadowy government agencies prying into our everyday lives via ubiquitous online and CCTV surveillance, are so commonplace now that most people ignore such news as "more of the same".
I know people like the examples of John and Jane cited above. In fact, I've gotten to know people who fit the stereotypes even better than John and Jane, some of them only by ominous sounding online pseudonyms -- good people on both sides of the cyberpunk/postcyberpunk divide, in real life, who each think of me as a good person but would likely regard each other only with horror and antagonism. I use the slightly toned-down examples above because too much information might just expose people to unwanted attention, and you might not believe the extreme examples I've seen in the real world.
If you ever want a better idea of what differentiates cyberpunk from postcyberpunk, you can find it on the Internet. If you're a postcyberpunk person, you should be happy to search for some examples on Google or Bing, but if you're more the cyberpunk type, perhaps you should use DuckDuckGo to avoid pervasive corporate surveillance.