src.rpms (aka source rpms) contain source tarballs, separate patches, separate scripts and specifications on how to compile all the includes stuff in order to build the binary rpms (*.i386.rpm, *.i686.rpm, *.athlon.rpm, noarch.rpm, ...) which you would install.
src.rpms are extracted like archives. They are not installed like binary rpms (which enter files into the RPM database).
The kernel src.rpm contains a loose collection of files, such as the original unmodified kernel from kernel.org plus hundreds of separate patches from Red Hat and from various sources. You would need to extract the kernel source archive and apply all the patches in exactly the same order and way as the src.rpm would do it upon running "rpmbuild --rebuild" on it.
On the contrary, the kernel-source binary rpm includes the fully patched ready-to-use kernel source tree that is used to build Red Hat's kernel versions found in their binary rpms. Inside /usr/src/linux-2.4 you can configure and build your own kernels and/or modules.