Difference between “comment_form_default_fields” AND “comment_form_fields”

Question

What is the difference between comment_form_default_fields and comment_form_fields?

Description in the official code reference seems to differ only by the word "default".

What's the difference in application? Which hook can I use to change the html output of fields for example? And what's the purpose of the other hook then?

Answer 1

Using comment_form_default_fields filter hook you can change email, author and url fields but cannot change comment field. And using comment_form_fields filter hook you can change all the 4 fields. You can use both filter hooks to change html.