NOTE: Red Hat Satellite 5 is still based on project spacewalk, but the next major release is moving to Katello, Pulp, Puppet and Foreman.
Although the SuSe management server is also an implementation of the open source project spacewalk I don't how similar that is to Red Hat's Satellite server implementation and how either of those compare to the vanilla open source project.
Errata advisories are Red Hat's way to distribute updates. It is safe to assume that the concept if similar to how others implement it.
You can consider a single errata advisory as a "container format" that contains the update to address a bug or security issue for one piece of software. Nearly always a single errata advisory results in more then just 1 single updated package, hence the need for a container format.
Second an errata advisory often impacts not only a single flavour of one major RHEL release, but multiple flavours i686 and x86_64 on RHEL 4, 5, 6 and RHEL7 server and workstation releases.
If you take for instance the Critical Security update for Shellshock RHSA-2014:1293-1 you'll see that the errata advisory contains a number of standard headers,
Type: Security Advisory
Issued on: 2014-09-24
Last updated on: 2014-09-24
Affected Products: Red Hat Enterprise Linux (v. 5 server)
Red Hat Enterprise Linux Desktop (v. 5 client)
Red Hat Enterprise Linux Desktop (v. 6)
Red Hat Enterprise Linux Desktop (v. 7)
CVEs cve.mitre.org: CVE-2014-6271
Followed by a human readable description of the issue(s) addressed in this errata advisory and the list of updated packages.
In this case the updated packages are a bash Source RPM and a number of regular binary rpm packages: the actual
bash rpm package, a
bash-debuginfo package and
bash-doc for each architecture and major release mentioned in the Affected Product list.
The operational concept of applying errata is that you want to report on security vulnerabilities that are patched and bugs that are fixed, rather than package versions that are installed.