I think it is the fact that if you look up calories in a calorie counter then it usually gives only one generic type of avocado. Plus, the calorie difference is much more considerable than with different apples. And this is not to do with size. Most eating apples have a similar amount of calories per gram.I'm surprised that anyone would think that they would be the same. Why would they be? Why would ask varieties of apples have the same number of calories (they have different levels of sugars in them) and do all varieties of nuts have the same calories? So why can't different avocados have different levels of calories?