Why are there two websites for Drupal?
Between these two websites, which one is the best to get quick responses?
When I ask questions in both websites, I am getting down-votes for asking the same question.
I posted the same question on both sites because I'm not getting answers in one of them, and I think most of the users visit only one site. If I post on just one site, I am probably missing many answers.
Stack Overflow is:
a question and answer site for professional and enthusiast programmers.
Drupal Answers is:
a question and answer site for Drupal developers and administrators
If you have a programming question that happens to be Drupal related, then SO may be the best place.
If you have a Drupal question that happens to involve programming, then DA is the best place.
That said, most Drupal related questions are best asked here, and don't cross post.
The difference between Stack Overflow and Drupal Answers is that the first is the site for programming questions, or questions about tools normally used from developers, while the latter is for questions with answers that apply uniquely to Drupal.
Since for a long time Stack Exchange was the only site where asking Drupal questions, some of the Drupal questions are tolerated on Stack Overflow even if they aren't about programming, but they are about the settings to use in a module, or which module use to achieve a specific task.
In general, Drupal Answers is for questions about Drupal, even when those questions don't involve code, but those questions need to be specific about Drupal. If you are asking which PHP function your code should use, that question is for Stack Overflow; if you are asking which Drupal function your code should use or which hook should be implemented, the question suits Drupal Answers.
http://drupal.stackexchange.com/." Also other Drupal tags have a reference to Drupal Answers: drupal, drupal-5, drupal-6. In other places, Stack Overflow doesn't have any reference to Drupal Answers because there are other sites where more questions are migrated. Stack Overflow cannot mention every site that could be interesting for the users, since that would mean the almost all the Stack Exchange network. :)