How are low-carbs diet vs low-calorie diet different?

Protein: Low carbohydrate diets tend to emphasize higher amounts of protein to get into 'ketosis' (not the same as keto-acidosis). This is a 'fat-burning' state. Low carb diets must be low-calorie as well, however, to work. Low calorie-diets alone simply lower overall calorie intake but those calories could be in the form of carbohydrates, protein or fat.