system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: What is the difference between Coke Zero and Diet Coke?

As far as I can tell, the ingredients are identical, and they seem to taste the same to me.
gpt
Very little.  Coke Zero was created because marketing at coke and elsewhere determined that men consider "Diet" drinks to be effeminate (girly), and so they made a product that could more easily be marketed towards men who are trying to limit calories.

They definitely have subtly different flavoring ingredients though, but the primary flavor is the same (aspartame).

Same with Pepsi MAX!  It's just marketing.