Imagine Compiler A has nine links to a chosen endpoint, while the compiler's pupil stands one transmission stage later and has ten.
If an independent scholar has nine links to that same endpoint, the counts match Compiler A: musāwāh. If the scholar has ten and the comparison is with Compiler A's pupil, it is muṣāfaḥah.
This schematic example illustrates the terminology. A real classification requires verification of every link, a consistent endpoint, and the actual count in each route.
Mentioning the “pupil” specifies the level of comparison; it does not mean that the later scholar literally heard from that particular pupil.