How do isotopes of a particular element primarily differ from one another?

Isotopes of a particular element primarily differ in the number of neutrons they contain. All isotopes of an element have the same atomic number, which is determined by the number of protons in the nucleus, and thus they share the same chemical properties. However, variations in the number of neutrons lead to differences in their atomic mass. For instance, carbon has isotopes such as carbon-12 and carbon-14; both have six protons, but carbon-12 has six neutrons while carbon-14 has eight. This difference in neutron count affects the stability and some physical properties of the isotopes, but not their chemical behavior.