There are two calorie values associated with workouts on the Apple Watch and iPhone: active calories and total calories. The difference between these two values is quite simple.
When you exercise and raise your heart rate, your body will burn more calories than at rest. These “extra” calories burned from physical activity are your ACTIVE calories.
Your TOTAL calories, on the other hand, includes both your ACTIVE calories and the calories your body burns at rest during that period of time.
For example: if your body burns 1,200 calories per day due to your BMR, that equates to 50 calories per hour. If you exercise for an hour and burn 300 ACTIVE calories, your body will still burn those 50 TMB calories, bringing your TOTAL calories to 350.
HOW ARE THEY REPORTED?
By default, most iPhone apps paired with a Bluetooth heart rate monitor report TOTAL calories (ACTIVE + REST) during a workout. .
On the iPhone, the app performs all the calculations based on a formula that uses your weight, age, gender, and average heart rate.
On the Apple Watch, it is completely different. Apple Watch performs all calorie calculations based on the personal information you entered in the Apple Watch app (black icon with side clock).
To verify these settings, open the Apple Watch app on your iPhone and then click on the “My Watch” tab. You will find your personal information in the HEALTH section.
The difference and explanation is here ! I hope you all will get it well.