Generally rpmbuild command generated using rpmbuild / directory is / root directory:
Here is what each directory:
~/rpmbuild
~ / Rpmbuild / SOURCES # placement packaged resources, including source code package file and patch files
~ / Rpmbuild / SPECS # documents placed SPEC
~ / Rpmbuild / BUILD # packing process working directory
~ / Rpmbuild / RPMS # packet storing the generated binary
~ / Rpmbuild / RPMS / i386 # stored packet generated by the i386 architecture,
~ / Rpmbuild / SRPMS # storing the generated source package