In my opinion, it is due to location. Bing returns 8 results on the first page, and DDG returns 10 results. At the top of the Bing page, I can see that Bing already takes my location into account (and it is precise, it is my city), so there is no box to tick. Once I tick the "location" box on DDG (it is only the country), I get 7 identical results out of 8 on the first page! The order is the same for results 1-4, the 5th result is different, the 6th result is identical, and results 7-8 are identical but their positions are swapped.