system
Given the following post, respond as if you're commenting on Reddit:
human
Which species has the most extreme genetic difference between male and female?  

Some animals (like cats), you can hardly tell the difference between a male and female, but then there are species like the angler fish, in which the male and female look like entirely separate species.  How extreme can it get?
gpt
That's two separate questions:

- Which species has the most extreme *genetic* difference between male and female?

- Which species has the most extreme *physical* or *apparent* difference between male and female?

AFAIK most species that have an extreme physical or apparent difference between male and female would only have a very small genetic difference between male and female.  (E.g.  XY  chromosome vs XX chromosome)