Is the feed that comes from Apple's RSS feed generator out of sync with the app store?
The "appstorefeeds.com" website is not associated with Apple. That appears to be a third-party site that creates its own feeds. My best guess is that it creates these feeds by scraping Apple's own feeds periodically. This type of operation is not something that can guarantee that all updates to Apple's own feeds will be updated live to "appstorefeeds.com". 

Not even within Apple's own website infrastructure you get that type of live syncing. I have seen Apple's website out of sync with what is displayed in the charts within iTunes. If you want the closest to the latest information, you should probably check from within iTunes. Hope this helps.