The key difference between parent and daughter isotopes is that a parent isotope undergoes radioactive decay to form a daughter isotope.
The terms parent and daughter isotopes come under the category of isotopes of chemical elements. Isotopes are different forms of a single chemical element. Therefore, isotopes have the same atomic number but different mass numbers because they differ from each other according to the number of neutrons present in their atomic nuclei. Among the isotopes of a chemical element, some or all of the isotopes are radioactive. They undergo radioactive decay to form different chemical elements.
