The table below enumerates the differences. For instance the spin of a photon is 1 and the spin of a 4 He atom is zero.
Many bosons can occupy a single quantum state.
This allows them to behave collectively and is responsible for the behavior of lasers and superfluid helium. Only one fermion can exist in a given quantum state. This is known as the Pauli exclusion principle, which is the subject of the next page. Any object that is composed of an even number of fermions is a boson, while any particle that is composed of an odd number of fermions is a fermion.