At the bottom of the article there's, under "See Also", a link to this page comparing RSS and Atom: https://www.intertwingly.net/wiki/pie/Rss20AndAtom10Compared...
It seems like the last update is from 2008, but the section on the differences has a few interesting items. I am not sure if it changed, but it says:
"The RSS 2.0 specification is copyrighted by Harvard University and is frozen. No significant changes can be made (although the specification is under a Creative Commons licence) and it is intended that future work be done under a different name; Atom is one example of such work."
The Wikipedia RSS page has also a small section comparing RSS and Atom: https://en.wikipedia.org/wiki/RSS#RSS_compared_with_Atom
"Technically, Atom has several advantages: less restrictive licensing, IANA-registered MIME type, XML namespace, URI support, RELAX NG support.[35]"
There is an npm package called astrojs-atom but i am not use it is official or safe.
Is there any astro core developer reading this, please add atom option addition to rss.
Some people forged ahead with a cleaned up RDF-based version and called it RSS 1.0, while other people went ahead with the ambiguities but without RDF and called it RSS 2.0. The person publishing RSS 2.0 considered it finished and refused to update it. There was drama.
A bunch of people decided that there was too much to clean up from within that mess and started a new format, Atom. This ended up being a much better spec. with an official RFC, but at this point everybody was calling any type of feed “RSS”, even if it was Atom.
If you have the choice, you should pick Atom.