The differentiation (at least at last time I looked at it), was that
the base packages that were bundled freeware (ie. gcc) were located
into /usr/sfw. The Companion CD typically put the unbundled freeware
into /opt/sfw instead.
If they moved a package from the companion CD to the base bundle, it
most likely changed paths from /opt/sfw to /usr/sfw as well.