* Chemistry Regents: This is a standardized exam administered in New York State to assess high school students' understanding of high school-level chemistry. It covers a specific curriculum defined by the New York State Education Department. Passing the Regents exam is often a graduation requirement.
* AP Chemistry: This is a college-level course and exam offered through the College Board. It's significantly more rigorous and covers a broader, deeper range of topics than the Regents exam. A high score on the AP Chemistry exam can earn college credit.
In short, the Regents exam is a state-level high school assessment, while AP Chemistry is a nationally recognized college-preparatory course. They are not interchangeable.