https://health.clevelandclinic.org/qa-can-you-burn-the-same-...
https://www.sciencedirect.com/science/article/abs/pii/S00219...
Equally, walking the same amount of time as a run expends less calories because of the greater effort involved in running to generate more external work.
What an odd question. Moving on...
I feel fine running a 5K in 30 minutes. If I cut that down to about 18 minutes, yeah, I sweat up a storm, too. I don't know why it would be unexpected that the faster you go over a set distance, the harder it's going to be.
> What an odd question.
Normal people would question this assertion, rightly so. Running takes more, unless you're walking at a running speed. Basic thermodynamics.
The last few months I've gone from a sedentary lifestyle to calorie counting and using an Apple Watch to track exercise with an intense 7-10 mile walk/run/hike 5-7x a week. With the weightloss I've experienced it seems relatively accurate (within 20%) but that's with 2-3 hours of exercise (not including weight lifting) per session.
But, there's at least "more legit than an Apple Watch" evidence that the calorie burn is that high; 6-8kcal per minute on Expert difficult [1], and some of the Expert+ tracks could easily burn more than that (and, I weigh much more than their Standard Reference Person).
I'm not the most fit person, but I've seen surprisingly little hard evidence that the Apple Watch grossly under or over-estimates calories burned. I imagine it starts getting worse at the extremes, and nothing is perfect, and everyone is different; its an area where more research would have unbelievably high leverage (Apple has sold, hundreds, of millions, of watches) (in fact: I'm sure they've done some of this research themselves).
EDIT: I weigh ~215 pounds