Returning an object from a function with different syntax in javascript

Question

I would like to know why we need to enclose the return statement element => ({title: element.Title, rating: element.imdbRating}) in parenthesis?

var mappedList = filteredList.map(element => ({title: element.Title, rating: element.imdbRating}))

If we could just do it in this way.

var mappedList = filteredList.map((element) => {
  return {title: element.Title, rating: element.imdbRating}
})