Strava and Health calories?

I am confused about the use of calories between Strava and the Health app. I have just converted to Strava from Endomondo. Endomondo would report calories to the health app and they would be the same. Strava logs my calories the same as Endomondo did within the app (i.e. the same number of calories per workout). However, when Strava reports to the Health app, the total calories are about half of what Strava indicates (e.g. on a walk this morning Strava said I burned 1347 calories but the health app only indicates 797 calories for this walk). What is up with that?

I am assuming that it has to do with Active Calories and Total Calories, but I don't understand why they are so different. With Endomondo, the calories in both Endomondo and the Health app were the same.

I am using an Apple Watch Series 5 to record my workouts in both Endomondo and Strava.

Please advise...

Michael