It loads only one single element to the memory. In other words, a list comprehension creates all elements right away and loads all of them into the memory.Ĭonversely, a generator expression creates a single element based on request. However, a generator expression returns a list of elements, one at a time, based on request.Ī list comprehension is eager while a generator expression is lazy. It means that a list comprehension returns a complete list of elements upfront. 2) Memory utilizationĪ list comprehension returns a list while a generator expression returns a generator object. In terms of syntax, a generator expression uses square brackets while a list comprehension uses parentheses (). Square_generator = (n** 2 for n in range(5)) 1) Syntax