In the HDP repository, you will find two different source RPM for each component.
For example, for Hadoop, you should find the following two RPMs:
hadoop-x.x.x.x.el6.src.rpm
hadoop-source-x.x.x.x.el6.i386.rpm
Two different packages serve the following purpose:
The src package is used to re-create the binary in a given environment. You can use the src package of a particular component if you want to rebuild RPM for that component.
The source package on the other hand, is used for reference or debuging purpose. The source package is particularly useful when you want to examine the source code of a particular component in a deployed cluster.