How is carbon-14 is different from carbon-12?

Carbon-12 and carbon-14 are two isotopes of the element carbon. The difference between carbon-12 and carbon-14 is the number of neutrons in each atom. The number given after the atom name (carbon) indicates the number of protons plus neutrons in an atom or ion. Atoms of both isotopes of carbon contain 6 protons.

C-12 has 6 protons and 6 neutrons

C-14 has 6 protons and 8 neutrons