i'm also a confused one bc i thought that the ultimate number of calories burned depended on the distance and terrain (uphill, flat, etc.). there might be SLIGHT differences in running v. walking, but i would assume them to be negligible.
it irks me that i only burn 150 calories walking 3 miles, but burn 300 or so when i run it... but then again i am not too accurate sometimes with the food entries, so maybe it evens out in the end

it's only an estimate after all.