Here's why:

* Neutron stars are incredibly dense remnants of massive stars that have exploded as supernovae. They are composed primarily of neutrons, packed extremely tightly together.

* Pulsars are rapidly rotating neutron stars that emit beams of radiation from their magnetic poles. These beams sweep across space, like a lighthouse, causing the star to appear to pulse as seen from Earth.

So, while all pulsars are neutron stars, not all neutron stars are pulsars. A neutron star needs to have a strong magnetic field and be spinning rapidly to be classified as a pulsar.