triode vs thermionic valve

triode and thermionic valve both are nouns.

Word	Noun	Adjective	Verb	Adverb
triode	Yes	No	No	No
thermionic valve	Yes	No	No	No

As nouns, thermionic valve is a hypernym of triode; that is, thermionic valve is a word with a broader meaning than triode:

triode: a thermionic vacuum tube having three electrodes; fluctuations of the charge on the grid control the flow from cathode to anode which makes amplification possible
thermionic valve: electronic device consisting of a system of electrodes arranged in an evacuated glass or metal envelope

Other hypernyms of triode include electron tube, thermionic tube, thermionic vacuum tube, tube, vacuum tube.

triode (noun)	thermionic valve (noun)
a thermionic vacuum tube having three electrodes; fluctuations of the charge on the grid control the flow from cathode to anode which makes amplification possible	electronic device consisting of a system of electrodes arranged in an evacuated glass or metal envelope