Linux is available in a dizzying array of distributions, each with their own versioning scheme. Most allow you to use the lsb_release tool to accurately identify the publisher and release version.
This is what the output of lsb_release looks like on Fedora 19:
[root@test1 ~]# lsb_release -ir Distributor ID: Fedora Release: 19
Here’s what you’d see on Red Hat Enterprise 6.5:
[root@test2 ~]$ lsb_release -ir Distributor ID: RedHatEnterpriseServer Release: 6.5
See the man page for more.