Because the first is a function returning function, and you have to think how that works, and the second one is just a simple function that returns a sum. Also

Because the first is a function returning function, and you have to think how that works, and the second one is just a simple function that returns a sum. Also, if you start a function with a word 'const' then it is less obvious that this is a function and not just a constant. In contrast, if you use a word 'function', then you understand what it is from the first word.