Difference:

C 12 has six neutrons, a stable nuclide,

C 13 has seven neutrons, a stable nuclide,

C 14 has eight neutrons and radionuclides, and its half-life is 5730 years.

Carbon ranges from 9 to 16. One * * has eight isotopes, C 12 and C 13 are stable, and the other six are radioactive.