Two related uses of the term “hadith science” should be distinguished. Transmission (riwayah) concerns the preservation, wording, and narration of reports. Hadith methodology (mustalah/dirayah) studies principles through which the condition of a report and the grounds for accepting or rejecting it are assessed.
An isnad is the chain leading back toward the original speaker; a matn is the narrated wording at the end of that chain.
Transmission asks, “What exactly was reported?” Methodology asks, “How reliable is the route and its narration?” These inquiries support one another without being identical.