Does Function Calls Depend on it's Placement in the Code Structure

Question

I wrote a function with a closure within it and i also wrote another function.

function argum(){
  let ist = arguments[0];
  return function(){
    return ist + ' ' + arguments[0]
  }
}

function logAll(){
    console.log(arguments.length);
}



var sh = argum('hello')
sh('world')

logAll(2,4,5,6,7)

As shown above, but i can't understand why the first call on the closure generates undefined. Meanwhile if i rewrite the code like this

function argum(){
  let ist = arguments[0];
  return function(){
    return ist + ' ' + arguments[0]
  }
}

function logAll(){
    console.log(arguments.length);
}

logAll(2,4,5,6,7)

var sh = argum('hello')
sh('world')

it seems to work fine. Any hint on what's happening there? Also use your browser dev tools to run this code, for a better understanding of what am asking.