Neutral atoms have the same number of electrons and protons. Atoms of an element that contain different numbers of neutrons are called isotopes. Each isotope of a given element has the same atomic number but a different mass number (A), which is the sum of the numbers of protons and neutrons.
An isotope differs from a neutral atom as it has more neutrons when compared to a neutral one. They are similar as both have equal amounts of protons and electrons.
