Whey do jobs on the RSS feed differ from jobs on the provider site, using the same keywords, categories?

Jobs available on a feed rarely have 1:1 relation with jobs on the provider site.

Since feeds usually contain a much limited number of jobs providers often use their own criteria to choose which jobs ​go into their RSS feed.

Also, since some feeds might not be updated often, they might not have the latest jobs being posted on the site.