Atoms of the same element that differ from one another are called isotopes.

Here's a breakdown:

* Element: A pure substance consisting of only one type of atom. For example, carbon is an element.

* Atom: The smallest unit of an element that retains the chemical properties of that element.

* Isotope: Atoms of the same element that have the same number of protons (and thus the same atomic number) but different numbers of neutrons. This results in different atomic masses.

For example, carbon-12 and carbon-14 are isotopes of carbon. They both have 6 protons, but carbon-12 has 6 neutrons, while carbon-14 has 8 neutrons.