How is a source RPM different from unpacking an RPM with rpm2cpio and cpio?

I am attempting to understand the use of a .srpm aka “source rpm” Red Hat Package Manager package. From what I understand so far, a .srpm is different from a standard .rpm in that it provides the source code and is commonly used during development. I am puzzled on why this is useful because if I run rpm2cpio ./myrpm-1.1-1.x86_64.rpm | cpio -idmv, I can still view the source code. As I understand, even standard RPMs pull down a .tar.gz/bz file which contains the source, and eventually builds this. Could you please clarify how source RPMs are different and why I would want to use one?

Go to Source
Author: the_endian