Why does Fitbit Records Different Exercise Adjustments then Fitness Pal

reedsey

I just recently started using Fitness Pal and have synced my Fitbit to this application. I generally walked at least 17000 steps when I work which according to Fitbit app I burned 2300 calories. Why does the fitness pal only show 21 and under exercise it show MFP iOS adjustment. Yesterday it showed 555 and under exercise it indicates Fitbit adjustment . I sync fitness pal and few times throughout the day.

Any advice or help would be greatly appreciated.