Whenever I create "RSS" feeds I always have the extention of '.xml', does that mean that it is just an XML feed or a RSS feed?
The extension of a file means nothing. Windows tried to make us belive that the extension makes the file, but that's wrong. You use whatever extension you want, while you send the right mimetype. So a .xml file can be RSS, or just plain XML without RSS...
melado is right, it doesn't have to end with .rss or anything like that. But more or less the industry standard seems to be that rss files end with a .xml extension. That way anyone could easily identify that file as an rss feed.