What is the difference between an isotope and a nuclide

The nucleus of an atom can be considered to be made up of protons and neutrons, collectively known as nucleons. A proton has a charge of -El and the number of protons in a nucleus determines the proton number (atomic number), Z, of the atom. The neutron bears no charge but has a similar mass to that of the proton. The number of electrons in a neutral atom is also equal to Z. Atoms with the same value of Z are chemically identical. The total number of nucleons in the nucleus is called the nucleon number (mass number), A. The number of neutrons in a nucleus need not be the same as the number of protons. 

Atoms with the same value of Z but different numbers of neutrons are known as isotopes of the element in question. Isotopes are represented by the symbol for example, the radioactive carbon isotope has a symbol C. 

A nuclide is any atomic species that has a specified nucleon number and proton number. Hence Be is a nuclide. 

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