How is a forum with Q&A functionality different from this one?

Question

CMS

Everyone writes that this site is a Q&A service, not a forum.
What are the main differences between a forum with Q&A functionality and this site?

Answer 1

Of course, there are also technical goodies, such as ratings, featured answers, and "invite an expert" buttons, but the main difference is ideological.
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Answer 2

In my opinion, a forum is a place where users can communicate on different topics and for different purposes, and getting an answer to their question is not the main task of the forum. To exchange opinions, to arrange a holivar, just to flood - this is all a forum.
And the Q&A service was created specifically to get an answer to a question, and preferably a qualified one (but this is not accurate). Moreover, participants from both sides receive a profit: the questioner receives knowledge/answer, the answerer gets what he does it for (+ to chsv, karma, just to move their brains or share experience).
Specifically, this service has its own unique features related to the topic (it), design (not to be confused with stackoverflow or answers.mail), mechanics for engagement (achievements and statistics).