I've used both a fair bit, so I'll try to add some perspective on the contrast between the sites. First: everything wax eagle said is true about this site.
People here take time to stop and smell the roses.
StackOverflow is fast-paced and not very rewarding. Averaging the scores of all answers in StackOverflow and RPG.SE (and making no attempts to remove outliers), StackOverflow answers net an average 18 reputation whereas RPG.SE ones earn 60 reputation.
At the time of writing, over a count of all answers' scores on Stack Overflow:
- 77.7% of Stack Overflow answers have 0, 1 or 2 points.
- Only 6.8% of answers on Stack Overflow have a score of 6 or more - our answers have a score slightly higher than that on average!
Simply put, there's not much incentive to write more than the absolute bare minimum answer on StackOverflow. Questions disappear off the front page in an hour, and everyone is just there to have a highly specific problem fixed that will often be of no use to you. In my experience, putting in any extra effort often goes unrewarded, and there might be only one or two votes given to any answer to the entire question. It's a race to the finish line. So, really, why bother writing more than a line?
Here, meanwhile, things move slower, competition isn't intense, and answers are more rewarding. Furthermore, a particular question is often widely applicable and could be quite interesting to a lot of viewers - and it's going to be there potentially getting their attention for quite a while! You have more time and more incentive to take your time making a good answer - not to mention that good answers often need to explain a lot, as wax eagle pointed out.
People here communicate well.
On StackOverflow, you often get a code dump and that's it: explanation is often found wanting, and ideas are very regularly not expressed clearly. Sometimes there's simply no motivation to go beyond the code dump (see the above section). Other times, however, this seems like poor communication on behalf of the user: that's as much as they feel it's necessary to express, or as much as they're capable of expressing.
Things don't tend to work that way here. Roleplayers, by the very nature of their hobby, must have pretty good social skills and must be able to communicate and express themselves well. An RPG player who is a terrible communicator is an outlier. Plus, there's rewards aplenty for a half-decent answer, so you can always get some reward for going that extra step or taking a few minutes to improve what you've written.
In IT, though, poor communication and social skills is part of a programmer stereotype that didn't form without substance. Rick Freedman elaborates in this extract from the Communication Skills section of The IT Consultant, a book published in 2000 (emphasis added):
Most IT professionals are intelligent individuals, folks who have mastered a difficult and demanding craft that has required diligent study and training. The idea that they cannot also be trained to communicate well is nonsense. People develop those skills for which they are mentored, compensated, and judged. Superior communication skills have not, until recently, been a requirement of the IT profession. In the mainframe days, IT teams worked in the infamous “glass room,” talking mostly among themselves, usually with a manager from the finance department to act as their interpreter. As computing moved to the desktop, however, and the ability to provide support and service to users in a language they could understand became a valuable skill, communication came to the forefront. Those technicians who could avoid jargon, who could communicate clearly with the secretary, clerk, salesperson, and manager, became valuable commodities. In short, the desktop PC revolution forced IT to become more consultative.
Thankfully, as you can gather from the parts I didn't emphasize, the "glass room" programmers and this stereotype are becoming a thing of the past, and communication skills are becoming increasingly important.