meson vs b-meson

meson and b-meson both are nouns.

Word	Noun	Adjective	Verb	Adverb
meson	Yes	No	No	No
b-meson	Yes	No	No	No

As nouns, b-meson is a hyponym of meson; that is, b-meson 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
b-meson: exceedingly short-lived meson

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

meson (noun)	b-meson (noun)
an elementary particle responsible for the forces in the atomic nucleus; a hadron with a baryon number of 0	exceedingly short-lived meson