What are the key concepts in organic chemistry that differentiate substitution and elimination reactions?

Substitution and elimination reactions are key concepts in organic chemistry that differ in their mechanisms and outcomes. In substitution reactions, one atom or group replaces another in a molecule, while in elimination reactions, a molecule loses atoms or groups to form a new compound. The key difference lies in the way the reactants interact and the products formed. Substitution reactions involve the replacement of one atom or group with another, while elimination reactions involve the removal of atoms or groups to form a double bond or a new compound. Understanding these concepts is crucial in predicting and controlling chemical reactions in organic chemistry.