Neutrons are the subatomic particles that are stored in the core of an atom with the protons. An atom is mostly empty space. At its center is a nucleus made up of particles made up of particles with a positive electric charge called protons and electrically neutral neutrons.
Isotopes is a word that gets thrown around in chemistry very often. Isotopes are different versions of an element or different versions of a certain kind of atom. Isotopes deal with atoms having different numbers of neutrons but the element will be the same but one may be heavier or lighter than another.