Very cool question, my friend. It makes me a little bit confused 😀
Ohm, at first glance, we will think that they are both the same in function. Both forum and Q&A are a place where people have the ability to ask questions about the product/service/problem they are interested and wait for responses.
Even if they look the same from the outside, they are very different on the inside.
An online forum is a discussion area. A topic of discussion is posted and people can respond, discuss, give their own ideas or evoke further conversations…Of course, you can get several answers but some of which will be nothing and the question ended inconclusively.
Although, the Q & A is similar to a “forum-style” of open, free for discussion like Quora or Stack Overflow but, on Q&A you will get specific answers that are 100% related to your question. It means that Q & A is very directed toward problem solving.
In addition, users can pick the best answer, which will then float to the top making it more easier for other users to find out.
Regarding the interaction and community, the Q & A isn’t as strong as forum.
I hope this answer is useful and have a nice day.