Isotopes are atoms of the same element that have the same number of protons but different numbers of neutrons. For example, carbon-12, carbon-13, and carbon-14 are all isotopes of carbon. They all have six protons, but carbon-12 has six neutrons, carbon-13 has seven neutrons, and carbon-14 has eight neutrons.

Isotones are atoms of different elements that have the same number of neutrons. For example, carbon-14, nitrogen-15, and oxygen-16 are all isotones. They all have eight neutrons, but carbon-14 has six protons, nitrogen-15 has seven protons, and oxygen-16 has eight protons.

Isobars are atoms of different elements that have the same mass number. For example, carbon-14, nitrogen-14, and oxygen-14 are all isobars. They all have 14 nucleons (protons and neutrons), but carbon-14 has six protons and eight neutrons, nitrogen-14 has seven protons and seven neutrons, and oxygen-14 has eight protons and six neutrons.