How is the hadith preserved?

Salam, I understand the great lengths the scholars of hadith did to preserve the hadith. Rather, I am aware that Allah wants to protect our deen, which I have seen include the preservation of the Sunnah. My question is, if there are clear differences of opinion about certain hadiths which may carry important legal ramifications, how do we reconcile that with the fact that the Sunnah was preserved and protected by Allah? Jazakallah khair, thank you all.