Really, there's a clearly delineated pattern as someone seems to pass through fandom and into the wider world of science fiction where the writers are considered people instead of gods and where they are *gasp* approachable.
Of course there are exceptions. You didn't think that I'd stereotype all these people without pointing that out, right?
Trekkies/Jedi: The outer level of fandom is the hardcore Star Trek and Star Wars fans, as I've already mentioned. They speak Klingon or have a full suit of Storm Trooper armor. They consume anything there is to consume from those lines and are what make Star Wars action figures so collectible.
The thing is, there is so much involved in these worlds and there are so many other people involved in them that they're isolated from the rest of Science Fiction a bit. Sometimes it seems like they can read twenty novels per year, but without touching on anything that doesn't happen in the Star Trek or Star Wars universe. They can talk and argue almost exclusively with other fans that share their passions, or they'll get bored.
The General Population are guys that like what they like. They won't show up in storm trooper armor, they don't regularly buy more than a few novels a year, and they don't seek out their favorite writers because they don't care enough. What they've read is usually what's on the display in the front of the Borders or Barnes & Noble. They usually don't have much of an idea of what's new and what isn't, and they're probably not too interested in the science fiction classics.
Novel Readers come next. By novel readers I mean the people that read novels that haven't been made into television shows or movies. These people sometimes keep abreast of the most current novels, but also read a lot of older works because they don't have to wait between book publications to continue the series that they started.
Since the universes in these novels usually aren't as expansive as the big universes they might have a favorite author or two, but they'll also read slightly wider. They'll usually have a better idea of the differences between hard science fiction and space opera or medieval fantasy and urban fantasy.
Years ago, this meant not knowing much about the writers themselves, or at least it did to me. I was more interested in the worlds that they created than knowing anything about their backgrounds. Usually have some idea of what is new and upcoming in the field of novels though, but won't have more than a tenuous connection to the current world of science fiction.
Short Story Readers are next. They are the ones on the bleeding cutting edge. They're on the lookout for the next big ideas (and sometimes the next big writers) and they don't have enough time for a novel to be published. They're the ones that subscribe to the 'zines and can claim that they've read something other than the Hugo and Nebula Novel nominees in categories other than "Best novel."
Aspiring Writers are those losing their fannish aspects. They will read anything because they want to learn, but they're the people that will travel to cons because they have friends attending and probably have already met one of their favorite authors already. They concentrate as much on their own work as other people's work. They'll keep a blog or a livejournal, work a day job, and dream of the day when they hit Orson Scott Card status.
Writers concentrate on their own work above all else. They read only a few selected favorite authors and authors they might blurb for because otherwise their time is spent avoiding the process of writing or, in Mercedes Lackey's case, doing apparently nothing else. They've overcome most of their fannish tendencies because they've been invited to the cons, they've been the Guest of Honor, and they've been recognized and had fans stop breathing.
They've gotten carpal tunnel from all the books they've been required to sign. They may be past the need for a day job, but still dream of hitting it George R. R. Martin or Tolkien big.
Publishers are a little different. Everyone they know is a writer or wants to be a writer. They haven't met someone that isn't in one of those groups in two years outside of bumping carts together in a supermarket. Their fannish tendencies have died witheringly under the mountains of the slush piles long ago. They are the unseen leaders, the powers that be, that are the arbiters of taste and great publication. They see all and know all about the publishing world.
Thus, they see nothing but people. No great writer or bad writer, not George Lucas himself, is going to leave them stuttering. They have complete immunity to science fiction writer fannish behavior, and can carry on an uninterrupted conversation with someone introduced as Joanne Murray. No living person has yet reported what dreams science fiction publishers may have about the future.
This is sort of related, but without the secret "publisher" level. Via Jeff.