I'm not framiliar with how the pclos guys used to build rpms, but I would think they're pretty close.
One major difference that I can think of would be the use of svn. We don't use svn, or cvs, so if you could build pclos rpms, mandriva, or fedora rpms, then I think you'd feel pretty much at home.
The last difference that I can think of, and this may not apply. In the beginning we used a lot of pclos rpms, but as of late we have moved most of our base rpm to that of Mdv.
Let me know if that helps