Protons, neutrons, electrons and positrons are compared using relative mass and relative charge. A proton has a relative mass of 1 and a relative charge of +1. A neutron has a relative mass of 1 and a relative charge of 0, so it is neutral.
An electron has a very small relative mass, about one two-thousandth of a proton, and a relative charge of −1. It is so light that the mass of the electrons in an atom can be ignored.
A positron is the antiparticle of the electron. It has the same very small mass as an electron but the opposite charge, +1. Positrons are emitted by some unstable nuclei, in a type of radiation called beta plus.