Weird. The results are in the exact same order for me when I clicked both of your links. The only difference is that the bootstrapshuffle.com result is below (or rather, on the second page) the stackoverflow result on Bing. Considering the former is specific to Bootstrap, it's less relevant than the stackoverflow result.

Anyways, DDG does mainly use Bing, but they also do their own modifications to the rankings, which is sometimes for better and sometimes for worse.