vacuum tube vs thermionic valve

vacuum tube and thermionic valve both are nouns.

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

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

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

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

vacuum 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