I log food only on MFP but when it sends over to fitbit the calories for food left to intake are different even though the goal if set the same on fitbit (0.7kg a week) and 1 1/2 lbs a week on MFP I know they are not exactly the same but rigt now fitbit says 592 left and MFP says 837 left??? over 300 cals is alot of difference so should I take notice of Fitbit cals?

My goal on Fitbit is set to 'kinda hard' (750 deficit) but what does the 750 deficit really mean? Its not on MFP?