The discussion clarifies the distinction between chemical and nuclear reactions. It emphasizes that Dalton's law states that chemicals do not change into atoms during a chemical reaction, which is accurate as chemical reactions involve the rearrangement of electrons, not changes to atomic nuclei. In contrast, fusion, such as the process occurring in stars where hydrogen combines to form helium, is classified as a nuclear reaction. This process involves high temperatures and the collision of atomic nuclei, resulting in the formation of new elements. The conversation also touches on fission, where a heavier nucleus splits into lighter elements. Overall, chemical reactions maintain the same elements but rearrange them, while nuclear reactions involve fundamental changes to the atomic structure.