| RSS |
ATOM |
| RSS 2.0 may contain either plain text or escaped HTML as a payload, with no way to indicate which of the two is provided. |
Atom in contrast uses an explicitly labeled (i.e. typed) "entry" (payload) container. It allows for a wider variety of payload types including plain text, escaped HTML, XHTML, XML, Base64-encoded binary, and references to external content such as documents, video and audio streams, and so forth. |
| RSS 2.0 has a <description> element which is commonly used to contain either the full text of an entry or just a synopsis (sometimes in the same feed), and which sometimes is absent. There is no built-in way to signal whether the contents are complete. |
Atom has separate <summary> and <content> elements. The summary is encouraged for accessibility reasons if the content is non-textual (e.g. audio) or non-local (i.e. identified by pointer). |
| RSS is not defined within an XML namespace. |
Atom is defined within an XML namespace. |
| RSS 2.0 does not have a means of differentiating between relative and non-relative URIs. |
Atom specifies use of the XML's built-in xml:base for relative URIs. |
| RSS 2.0's use of its own "language" element. |
Atom uses XML's built-in xml:lang attribute.
In Atom, it is mandatory that each entry have a globally unique ID, which is important for reliable updating of entries. |
| RSS 2.0 only supports full feed documents. The only recognized form of RSS 2.0 is an <rss> document. |
Atom 1.0 allows standalone Atom Entry documents. These could be transferred using any network protocol, for example XMPP. Atom also has support for aggregated feeds, allowing entries to point back to the feed they came from when they are included into other feeds. |
| The date format in RSS 2.0 was underspecified and has led to many different formats being used. |
Atom specifies that dates be in the format described in RFC 3339 (which is a subset of ISO 8601). |
| RSS 2.0 feeds are often sent as application/rss+xml, although it is not a registered MIME-type. |
Atom 1.0 has IANA-registered MIME-type. |
| RSS 2.0 does not include an XML schema. |
Atom 1.0 includes an XML schema. |
| RSS 2.0 is not standardized by any standards body. Furthermore according to its copyright it may not be modified. |
Atom is an open and evolvable standard developed through the IETF standardization process. |
RSS autodiscovery has been implemented several times in different ways, often relies on unregistered (thus invalid) application/rss+xml MIME type, and has never been standardized. This is a common source of difficulty for non-technical users. |
Atom standardizes autodiscovery. The application/atom+xml MIME Type is registered with IANA. Additionally, Atom feeds contain a “self” pointer, so a newsreader can auto-subscribe given only the contents of the feed, based on Web-standard dispatching techniques. |
