pulsar vs neutron star

pulsar and neutron star both are nouns.

Word	Noun	Adjective	Verb	Adverb
pulsar	Yes	No	No	No
neutron star	Yes	No	No	No

As nouns, neutron star is a hypernym of pulsar; that is, neutron star is a word with a broader meaning than pulsar:

pulsar: a degenerate neutron star; small and extremely dense; rotates very fast and emits regular pulses of polarized radiation
neutron star: a star that has collapsed under its own gravity; it is composed of neutrons

pulsar (noun)	neutron star (noun)
a degenerate neutron star; small and extremely dense; rotates very fast and emits regular pulses of polarized radiation	a star that has collapsed under its own gravity; it is composed of neutrons