meson vs psi particle

meson and psi particle both are nouns.

Word	Noun	Adjective	Verb	Adverb
meson	Yes	No	No	No
psi particle	Yes	No	No	No

As nouns, psi particle is a hyponym of meson; that is, psi particle is a word with a more specific, narrower meaning than meson:

meson: an elementary particle responsible for the forces in the atomic nucleus; a hadron with a baryon number of 0
psi particle: a neutral meson with a large mass

Other hyponyms of meson include b-meson, J particle, k-meson, K particle, kaon, kappa-meson, pi-meson, pion.

meson (noun)	psi particle (noun)
an elementary particle responsible for the forces in the atomic nucleus; a hadron with a baryon number of 0	a neutral meson with a large mass