jawbone calories confusion

have a problem with my jawbone calories.
they show me a difference of 600+calories each day which is not really helpfull for my calorie goals. mfp tell me to stay at 1590cal to loose 1lbs per week.jawbone adds another 660 because the sync tells me that I burn est. over 3000 aday but my jawbone app itself tell me an estimated burn of 1860cal... why and what is wrong there?