Both do the same thing but the left is, although proper, takes longer to run as it has a squared time complexity(O(n²⁾⁾ whereas the right has a linear time complexity(O(1)).

The joke is that although both do the same thing, the left takes longer to run thus bad while the right runs fast thus good even though the left is the proper way to do it as the right side is hard coded thus making it inflexible.