Mastodon only processes the content of Notes up to a default character limit of 500 characters
this is only for local posts. remote Notes can have any character limit.
the difference between a Note and an Article is not well-defined, but was intended such that an Article is to be published as an independent unit of syndication (like HTML article). nowadays on mastodon-fedi the Note is what gets syndicated fully whereas the Article is linkified for viewing on the original site. it would probably make more sense to treat as such:
- Article: self-contained formatted text, can be viewed on its own
- Note: one-off text message, makes more sense in context
so this suggests Note (with full contents) for forum federation. but again, it’s not formally defined. one could also use Article as MDN advises (or at least <article> anyway)
see also: