Calories

My Samsung Watch Ultra 2 tracks my energy expenditure. I’ve noticed something strange. If I go for a long walk with the dog in the morning, without recording the walk, the Watch tells me on my return that I’ve burned around 200 kcal from the activity.

If I record that same walk as a sport activity (Walking), it easily shows 350 kcal as burnt. Even though it was the same walk. How is that possible?