Vkohli,
you may need to look into your VO2max on both the watch and the software. It seems that the calories estimate is off if the VO2max is set either too high or too low for where you really are. I had Eddie Fletcher on the
Suunto Discussions look at my logs and help me determine my VO2max from few runs and race results. Basically the recommendation is in live with VDOT tables from Daniels. After setting my VO2max to that value and setting my activity level according to my weekly
training hours I see much closer calories burned between the watch and FB athlete/STrM.