Carbon-12 and Carbon-14 are isotopes; it means that they have no protons

they have a different number of neutrons

they have a different number of electrons

they have the same atomic mass

A :-) Isotopes are forms of the same element with equal numbers of protons but different numbers of neutrons. For example, both carbon-12 and carbon-14 have 6 protons. But carbon-12 has 6 neutrons while carbon-14 has 8 neutrons. By definition, carbon-12, carbon-13 and carbon-14 are all isotopes of the carbon.