The structure of the build repos on buildlogs.centos.org are as follows:
RC and GA build trees: c7.00.02/ c7.00.03/ c7-00.04/
CentOS 7 Extras: c7-extras/
CentOS 7 Plus: c7-plus/ <==Not there yet, will be when we build the plus kernel later today
CentOS 7 Updates: c7-updates/
So, everything that goes on the CentOS 7 ISOs (and are the same versions as the RHEL7 GA release) will come from c7.00.02, c7.00.03, and c7-00.04 (except the actual secureboot signed content that KB mentioned earlier).
Anything that is an updated package form those on the ISOs will come from c7-updates.
The centos/ directory is the actual testing tree(s) for the open qa process and will eventually go away once we have a GA release .. however, the build repos (which are actually the staged repos used for building the packages via mock) and listed above will remain indefinitely to show the RPMs, SRPMs, and logs from mock used to produce CentOS 7.
Thanks, Johnny Hughes