electron tube vs thermionic valve

electron tube and thermionic valve both are nouns.

Word	Noun	Adjective	Verb	Adverb
electron tube	Yes	No	No	No
thermionic valve	Yes	No	No	No

As nouns, electron tube and thermionic valve are synonyms defined as:

electron tube and thermionic valve: electronic device consisting of a system of electrodes arranged in an evacuated glass or metal envelope

Other synonyms of electron tube include thermionic tube, thermionic vacuum tube, tube, vacuum tube.

electron tube (noun)	thermionic valve (noun)
electronic device consisting of a system of electrodes arranged in an evacuated glass or metal envelope	electronic device consisting of a system of electrodes arranged in an evacuated glass or metal envelope