This is the website to explain precisely how different between the RSS and ATOM.
| RSS 2.0 | Atom 1.0 | Comments |
| rss | - | Vestigial in RSS |
| channel | feed | |
| title | title | |
| link | link | Atom defines an extensible family of rel values |
| description | subtitle | |
| language | - | Atom uses standard xml:lang attribute |
| copyright | rights | |
| webMaster | - | |
| managingEditor | author or contributor | |
| pubDate | published (in entry) | Atom has no feed-level equivalent |
| lastBuildDate (in channel) | updated | RSS has no item-level equivalent |
| category | category | |
| generator | generator | |
| docs | - | |
| cloud | - | |
| ttl | - | <ttl> is problematic, prefer HTTP 1.1 cache control |
| image | logo | Atom recommends 2:1 aspect ratio |
| - | icon | As in favicon.ico |
| rating | - | |
| textInput | - | |
| skipHours | - | |
| skipDays | - | |
| item | entry | |
| author | author | |
| - | contributor | |
| description | summary and/or content | depending on whether full content is provided |
| comments | - | |
| enclosure | - | rel="enclosure" on <link> in Atom |
| guid | id | |
| source | - | rel="via" on <link> in Atom |
| - | source | Container for feed-level metadata to support aggregation |
for more information http://www.intertwingly.net/wiki/pie/Rss20AndAtom10Compared