thermion vs subatomic particle

thermion and subatomic particle both are nouns.

Word	Noun	Adjective	Verb	Adverb
thermion	Yes	No	No	No
subatomic particle	Yes	No	No	No

As nouns, subatomic particle is a hypernym of thermion; that is, subatomic particle is a word with a broader meaning than thermion:

thermion: an electrically charged particle (electron or ion) emitted by a substance at a high temperature
subatomic particle: a body having finite mass and internal structure but negligible dimensions

Other hypernyms of thermion include particle.

thermion (noun)	subatomic particle (noun)
an electrically charged particle (electron or ion) emitted by a substance at a high temperature	a body having finite mass and internal structure but negligible dimensions