The Science calorie is with a lower case c, and it is the amount of heat needed to raise one gram of water by 1 degree Celsius. The Food calorie is written with an upper case c, and it is the amount of heat needed to raise one KILOgram of water by 1 degree Celsius.
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A science calorie is a single unit count of a single eatable item. A food count is the generalised count of the ingredients present in that food.