Elliptical Workout

I recently moved up to a higher intensity on my elliptical training. Doing so I noticed that the watch is tracking less calories being burnt even though I am work with a much greater resistance. Is the only thing that registers on Apple Watch 3 the motion of my arms? My elliptical is telling me I am taking around the same amount of steps as well as traveling around the same overall distance but the caloric difference is astronomical. On my Elliptical I am registering 486 calories burnt and my watch reflects 395 total for the work out and only 344 active calories. (oddly enough my work out just yesterday on the less intense selection game me 353 active calories) Something is amiss :-/