You can also be both.
Like every newspaper website that has a comment section. They are responsible for the parts they publish but not the user generated comments. There is no legal requirement to be one or the other.
For whatever reason, most people seem to get this backwards.
Here is the relevant legal code Section 230 C1: “No provider or user of an interactive computer service, a platform, shall be treated as the publisher or speaker of any information provided by another information content provider.”
There is nothing in the law that says a publisher is responsible for user generated contact (even if they moderate it). In fact the law says just the opposite.
Edit: added note in parenthesis