Confused about "creating an assistant file" vs just adding adding file_id during creation

When creating an assistant you can add a file_id into the file_ids array (as documented in the Create Assistant page.

However there’s also a Create assistant file section where you can link a File with an Assistant. Is there any difference between the two approaches or are they one and the same thing (just two different ways of adding a file to an assistant)?

Could someone please clarify this for me?