firefox version numbering in different repos

I don't get the version numbering philosophy of the different repos containing mozilla firefox:

the update repo contains 30.0-29.1, last modified 20 Jun 2014
(http://download.opensuse.org/update/...rpm.mirrorlist)

the mozilla repo contains 30.0-3.2, which has a lower version number, but is modified later: 05 Jul 2014
(http://download.opensuse.org/reposit...rpm.mirrorlist)

the mozilla factory repo contains 30.0-391, an even higher version number, modified an the same date: 05 Jul 2014
(http://download.opensuse.org/reposit...rpm.mirrorlist)

can anyone elucidate the resoning behind that?
which repo would I select if I want the latest but stable version?