I think dongalong's description of a "structured" personality is a bit vague, and it seems to me everyone is reading into it either based on themselves, a colleague, or someone else they know. The people that have been described thus far could actually have little in common with the woman dongalong is talking about.
At the place where I work, there are lots of people who socialize and are "chatty." They also give the impression that they don't get much work done. One woman who sits near me is almost always in conversation with someone. She never seems to work at all. These sort of people aren't performing so badly as to get fired, but they don't get promoted, either.
I'm at the opposite extreme. I come in, work a minimum of 8 solid hours (not a few hours of work and a few hours of gossip), rarely talk to anyone unless I have to, and when I feel like I've gotten enough work done (usually long after everyone else has left for the day) I leave.
I have received feedback from my supervisors that I need to be a little bit more friendly with people, particularly when making requests from another departments. One of my supervisors suggested that I try to chat people up a bit, show an interest in them as people, ask about how their kids are doing, etc. He also gave me an article about "emotional IQ."
But, the truth is, I have no interest in getting to know my colleagues as people, and I feel uncomfortable and dishonest trying to fake it. It's not that I particularly dislike anyone. In fact, there are some people whom I'm rather fond of, in my own way. But for the most part, I find my coworkers mostly disinteresting. Few of them are my age, and those that are are straight and married and all they ever talk about is their kids. I have nothing in common with them. Consequently, I have no friends at work, and I don't socialize with my coworkers outside of work.
I'd be perfectly content with that if I had friends outside of work. Unfortunately, I don't, but that's another story.